RPM Monsters

Even though Power Rangers RPM is one of the best Power Rangers seasons of all time, my biggest gripe from this season is the monsters not talk. While the monsters talk in Go-onger, there are only three monsters (Water Hoser, Sat-Bot and Dyna-Bot) that talk but most of them don't. Does it make any sense? I hated that idea. Is there a reason why they don't talk?