It’s really very simply. If you have a device that performs a single function, it probably does it better than a device that tries to do multiple things. The MF device won’t be the best at any one thing, hence the compromise.
Of course, the other potential issue is that if any one component breaks, you may need to replace the entire unit. If you had separate devices you just replace that one device. So in the case of the Bravo you have a TQ, trim wheel, annunciator panel, and some multifunction switches. The more you put in, the more there is to break.