Why did the Chachamim uproot the mitzvas of shofar and lulav on Shabbos, but not the mitzvah of matzah when Pesach falls on Shabbos?
There are a number of answers given for this question. Here are some.
Netziv (Vayakhel Sheilta L’purim 21) that chazal only made the gezeira for a mitzva done by day, but not on a mitzva done at night since it isn’t the norm for people to go out at night.
Hamoadim B’halacha 2 pg. 410 says that the gemora in Rosh Hashana 29b that the reason for the gezeira on the shofar was because not everyone knows how to blow shofar. This doesn’t apply to the eating of matzoh. Even if he would have to learn how to make the bracha from the Rov, but the actual performance of the mitzva doesn’t need guidance. See Tevusa Hasadeh Shar Birkas Hamoadim 1-18.