They've known about the lame capabilities of msgbox(), questdlg(), warndlg(), errordlg(), inputdlg() for ages and they've never chosen to enhance them so I guess they just don't want to, despite being a pain to the users for decades. I know other functions like title(), text(), xlabel(), etc. have options like 'FontSize', 'FontWeight', 'ForegroundColor', etc. but for some reason unknown to me they don't seem to want to offer those options to dialog boxes that ask for user input.
If you start GUIDE, one of the options is a custom dialog box where you have complete control over all of that, so I guess that's how they want you to do it. I know it seems like an overly complicated way to do a simple dialog box, but that seems to be what they want us to do. Grrrrrr.