You know, in universe I share your skepticism, but com'on, it's pretty hard making a sci-fi tv series in which each new alien you meet speaks a different language. Seriously, we'd all be lost as to what's going on and half of each episode would have to be spend on figuring out the language of the week. I have little issue with everyone seemingly speaking English and it being explained by the UT.
It doesn't deterr from the sci fi aspect either. Sci fi isn't about languages or rubber on faces (though it would've been nice to see a little more creativity in the latter), it's about the stories themselves.
I quite liked Who Watches the Watchers?, but I think they could've made it more interesting by giving Troi a more active role and more dramatic if they'd had Troi be shot and the Mintakens expecting Picard to heal her. Most of all, this is one of those episodes that are perfect to reference to later in the show. It would've been nice to see any of the senior staff tease "The Picard" about this later on.