Courtroom dramas suck, usually, because they're nothing but cheap talk. Sooner or later, though, TNG was going to have to have one and it turned out not to be as insufferable as it could've been. As a Data episode, its strength is in the realisation that even in the "enlightened" future, people's rights can be - inadvertantly - oppressed. Even an entire class of people, whether based on status, or physicality, whatever. And that this possibility was approached so early on in TNG's run is "fascinating" to me. This should've never even been brought up, in-universe, considering how accepting and tolerant ALL of Humanity is - and not just in STARFLEET.
The other aspect that makes "Measure of a Man" work is the test of friendship and that it was done with the right tonality. It wasn't some cheesey, family friendly, wholesome entertainment manner - Riker's been ordered to make it possible for STARFLEET to strip Data of all of his rights. If not, then Data would just lose them by default. And there are many aspects of Real Life that this could be an analogy for, like intervention for addiction, for example. Or even just about how blurred the lines are between professionalism and fraternisation in the workplace.
All kinds of possibilities are touched on by this that give added meaning and depth to an episode that, even superficially, is "about something." At the end of the day though, yes, we're subjected to an episode that's all talk, but how interesting it is that someone's very existance might depend so greatly on "just talk." And, personally, I love how the JAG Officer just wants to rape Picard, every other time she runs into him, this episode. She's no Bev, but she was kind of cool ...