Rabbi Yechiel Michel HaLevi Epstien
author of the Aruch HaShulchan bio
Before we begin let us consider the following.
There is, to the best of my research, and I have researched this with many competent rabbis; no Halachic discussion about and certainly none that suggests, that Matza should be hard. The great Poskim, the MBerura, Aruch HaShulchan and ShAruch HaRav, go out of their way to mention that Matza can be soft and make no mention of Matza being hard.
Secondly, once they DO mention soft Matza, these Poskim, if they had any reason to oppose it, would qualify by saying, "however, this is not the custom in our community." There is no such qualification.
Thirdly, they have gone out of their way to mention soft Matza. If they were opposed to soft Matza, they would not add mention it, or would at the very least, qualify it. It is clear that soft Matza is a perfectly normal and acceptable product for Jews of all backgrounds.
Furthermore, in the comprehensive Halachic discussion relating to determining when Matza is adequately baked, the criteria are applicable exclusively to soft Matza. For example, poking a finger through the baked Matza or tearing it to see if there are any stringy doughy threads stretching between the torn pieces. Yet here too, the great Ashkenasi Poskim do not indicate that these are no longer applicable to "our" Matza.