Shabbat Chol HaMoed Pesach

The matzah that we eat on Pesach is made from flour of the five grains, such as wheat and barley.
Bnei Ashkenaz have the custom not to eat foods made from kitniyos, because of the concern that chametz might become mixed in with them.
The question is as follows, just as with the five grains, if we bake the dough according to the halachos of matzah, it does not become chametz. Therefore we are able to eat matzah made from the five grains on Pesach.
If so, why don’t we also bake matzos made from kitniyos flour, following the halachos of matzah, and eat them on Pesach? (Not on Leil HaSeder, but at least during the rest of the days of Pesach).
Yet in practice we find that we do not eat kitniyos at all, even if it would be prepared according to the halachos of matzah, unlike the five grains from which we do bake matzah.
So the question is, why is the gezeirah of kitniyos treated more strictly than the five grains themselves, from which we actually make matzah on Pesach?

The Gemara in Pesachim (35a) writes that only the five grains can become chametz. However, rice and millet (which are included in kitniyos) do not undergo a process of chimutz; rather, they only spoil. The Gemara states:

“Only things that can become chametz can be used to fulfill the mitzvah of matzah. These exclude rice and millet, which do not become chametz but rather spoil.”

We see from the Gemara that kitniyos do not become chametz. They do not ferment, and therefore they cannot become chametz.
If so, what is the reason that we do not eat kitniyos on Pesach? If it is not possible for kitniyos to become chametz, then what is the source and reason for the custom not to eat them?
We find that the Rishonim give two reasons for this prohibition.
The Ritva in Pesachim (35a) writes that since kitniyos and wheat kernels can look very similar, it can be very difficult to distinguish between them. As a result, it is possible that even a single kernel of wheat could become mixed in together with the kernels of kitniyos.
As we know, on Pesach chametz is assur b’mashahu, meaning that even the smallest amount of chametz can forbid an entire dish. Therefore, if even one kernel of wheat becomes mixed in with the kitniyos, the entire dish becomes forbidden.
Because of this concern, Chazal made a takkanah not to eat kitniyos at all, so that a person should not mistakenly come to eat a dish that may contain chametz.
The Mordechai in Pesachim gives a different reason. According to him, the concern is not that chametz may become mixed into the kernels of kitniyos. Rather, the reason is that foods made from kitniyos often look very similar to foods made from the five grains.
In fact, he writes that in some places people even bake bread from kitniyos flour, which looks like regular bread made from chametz. Therefore, if people see someone eating such bread or dishes on Pesach, they may think that it is permitted to eat chametz bread or chametz dishes on Pesach, since the foods look so similar.
Therefore, Chazal instituted the gezeirah not to eat kitniyos at all, so that people should not mistakenly come to think that chametz foods are permitted on Pesach.
The following are quotes from the Rishonim mentioned.
The Ritva writes:

Even though rice itself does not become chametz, one must be very careful, because wheat grains are often found mixed together with it. If even one grain remains, the entire cooked dish could become forbidden due to chametz. Therefore, it must be checked carefully again and again. Since this mixture is very common, many pious people refrain from eating cooked rice on Pesach.

The Mordechai writes (Siman 588):

It seems proper to maintain the custom and forbid all kitniyos on Pesach, not because they become chametz, but as a decree. Since kitniyos are commonly cooked as porridge and grains are also cooked as porridge, if kitniyos were permitted people might come to permit grain porridge as well. Furthermore, in some places people make bread from kitniyos similar to bread made from the five grains, and this could lead to confusion among those who are not learned.

The Mishnah Berurah (Siman 453:7) brings both of these reasons as accepted halacha.
Circling back to our question, according to both reasons given by the Ritva and the Mordechai, it would seem that we should be able to eat matzos made from kitniyos, since matzos baked according to the halachos of matzah do not resemble chametz bread.
Furthermore, if matzah made from kitniyos is prepared in the same way as regular matzah and baked within 18 minutes, there should be no concern of chimutz. Even if a kernel of wheat were to become mixed in, as the Ritva mentions, it would still not become chametz, since the dough would be baked within the time required by the halachos of matzah.
If so, why do we not make and eat matzos from kitniyos on Pesach? Not on Leil HaSeder, but at least during the rest of the days of Pesach.

Indeed, we find that the Chayei Adam (Klal 127) writes that it is permitted to bake matzah from kitniyos during the rest of Pesach. He writes:

“It is permitted to grind them, bake them like matzos, and eat them.”

However, HaGaon Rav Amrom Fried shlit”a explains that: In practice one should not be lenient to make matzah from kitniyos. The reason is that people find it difficult to understand the distinction between kitniyos and matzah made from kitniyos. Therefore, the custom is to prohibit even matzah made from kitniyos, as written in the responsa Shoel U’Meishiv (Vol. 1, Siman 175, p. 63), that one should not be lenient like the opinion of the Chayei Adam, since the custom has been to treat this as forbidden. See there for additional reasons for this custom.
The Shoel U’Meishiv explains that since matzah made from kitniyos would be baked according to the halachos of matzah, people might think that it is actual matzah with which one can fulfill the mitzvah on the night of Pesach.
Moreover, people might reason that since kitniyos flour cannot become chametz, it would actually be even more suitable to fulfill the mitzvah of matzah.
The Shoel U’Meishiv writes that once the rabbis allowed people to buy beans to eat on Pesach, and they ended up cooking them together with type of noodles, as they were used to doing during the year. Because of the great confusion that resulted, the rabbis later retracted the permission.
He writes that after that Pesach the community experienced a lot of tragedy with many illnesses, Hashem yeracheim, and the rabbis attributed this to the leniency that they issued on Pesach.
He concludes that we must be extremely careful not to be lenient with the takanot (protective fences) established by the Sages.
…In Conclusion….
We see from everything we have learned about kitniyos that Chazal were able to foresee many potential problems that others might not have thought about. Through their decrees they protected Am Yisrael from the prohibition of chametz. , and that even in times when people thought there might be a way to permit something, it ultimately led to a very serious michshol.
This teaches us an important lesson: we must always listen to the words of the sages, appreciate the safeguards they established, and then we can be confident that we are doing the right thing.

On behalf of the entire Sheilot team, we wish you a Shabbos Shalom uMevorach and a Chag Kasher VeSameach