For us Liberal Jews, the most interesting aspect of the discussion is the reason, which is given for the ruling that “the mitzvah of matzah cannot be fulfilled with Matzot Ashirah.” It is that we are commanded to eat “the bread of poverty” (as stated in Deuteronomy 16:3). So the question is whether in the 21st century, Matzah Ashirah can be considered to be “the bread of poverty.” How would we answer that question?
One indicator may be the cost of the matzah – of course, this varies greatly depending on where you are in the country but generally speaking Matzah Ashirah is significantly more expensive than regular matzah. However, by this logic, we most certainly shouldn’t be using Shmurah Matzah, which is even more expensive but which many authorities claim is the only matzah that one may use to fulfill the obligation of eating matzah at the seder. And if we were really trying to eat “the bread of poverty,” it would probably have to be a supermarket-brand value loaf of white sliced bread – I think we would all agree that this would feel rather odd at a seder. So if cost cannot act as useful guidance, it seems to be left to our intention when eating the matzah and our personal understanding of what it means to eat “the bread of poverty” which must guide us in knowing if one has fulfilled the mitzvah.
So have you fulfilled the mitzvah of eating matzah at the seder even though it was with Matzah Ashirah? From a Liberal Jewish perspective, I would say it depends – if you reflected on the meaning of eating matzah during the seder, the answer surely must be yes. But if you just ate the matzah to tick a box on some imaginary seder checklist, the answer is probably no and it would have likewise been no had you eaten Shmurah Matzah or any other regular Matzah.