Mishna Berurah- acc. to Beis Yosef not derech eretz to bite into something bigger than a k’beitza
Again, not derech eretz doesn’t mean that it’s an issur. And furthermore, whether or not something is considered derech eretz can depend heavily on cultural norms.
Maharsha- it is proper to always eat with utensils
Did the Maharsha eat his matzah with utensils? And, even if he did, is it possible that that was the cultural norm in the place and time where he lived? It is possible that there were few, if any, foods in his time where it would have been considered acceptable to do so but perhaps, in our time, such foods exist?
Or do you really think the Maharsha would say that one should cut up his black and white cookie and his Snickers bar with a fork and knife?
The Wolf