Personally, I think Data was kind of played out as a character anyway. The emotion chip had the potential to send his character in new directions, but each successive movie undermined that transition more and more and reset him back to his old status quo. And after that, what more was there to say? Where could you take him as a character from that point?
Didn't you just answer your own question by saying there was unutilized potential?
There was potential, but it was negated by the movies' progressive retconning of Data back to an emotionless, static being. NEM had Data state outright that he felt nothing. The books' explanation for that was that he had the emotion chip removed in the year before NEM. I really don't see much that could be done with the character after that. Well, maybe if you jumped forward and explored how he dealt with outliving all his friends, but there have been a couple of excellent SNW stories that did that, and it isn't really a viable basis for storytelling within the regular TNG context.
I don't know but somehow the "not bringing back dead people"-statement is sort of contradicted by the ENT-post TATV-books...
Every rule has its exceptions. The death of Trip was so ineptly handled onscreen that it required reinterpretation simply in order to make sense of what we saw. Trip's behavior in the holodeck simulation Riker watched was totally illogical; the threat he sacrificed himself for was ridiculously minor, there was an inexplicable lack of security personnel around, and he should've been able to devise a less lethal way of stopping the pirates. Also the chronology of the episode is confused because it was originally written to take place in the current season but was hastily reworked to be six years later once the show was cancelled, so there are inconsistencies that needed to be addressed. Plus there's the fact that we didn't actually see him die, even in the simulation; the last time we saw him, he was alive and being rolled into the medical chamber, and after that we only see characters talking as if he were dead. And of course the whole thing was a piece of historical fiction/reconstruction being watched by someone over 200 years later. So the way it was presented virtually
compels the notion that there's a hidden truth underlying what we were shown.
Personally, maybe I would've done it in such a way that Trip did die, but in a way that made more sense and had more purpose than what we saw. But given that it pretty much had to be a major and deliberate obfuscation of the truth (since I don't think Riker would've chosen such an inept reconstruction of history if there'd been a more accurate one available), it's logical that there's a big secret behind it, and having the allegedly dead guy actually be alive works in that context -- especially when we only got hearsay evidence of his death to begin with.
No such mitigating factors apply in Data's case. We saw him standing right next to the thalaron generator only a couple of seconds before it went up in a monumental explosion. That's cut and dried. It would take a massively convoluted and implausible retcon to establish his survival in any form. Unlike in Trip's case, where it's the onscreen version that's massively convoluted and implausible.