I agree and disagree here. I think the movie does clearly suffer for it as a movie, but I think if we're to look at the story this movie chose to tell-- which I think is fair, her absence entirely would've had a detrimental effect on Ben's arc and her relationship with Rey is basically the only thing that is able to justify Rey deciding to take the Skywalker name at the end. And those things are on kind of wobbly ground to begin with.
I guess I'm of two minds about this movie. As a lifelong Star Wars fan who's very invested in the overall narrative of the 9 films, I overall liked the story they chose to tell and I think a lot of those story beats felt right to me when I reflect on them. As a film fan, the issues are obvious, and it took me out of enjoying the ride on my first viewing. And I totally get the complaints about fan service and the movie feeling unoriginal, etc. But while it's 100% fair to criticize this film on its own merits, I guess I feel more inclined to cut the movie some slack when I recognize the crazy task it had on its plate of wrapping up 9 films, which already have a pretty wonky mythology. I just think the movie should've allowed itself more runtime. I seriously think even an extra 10-15 minutes could've done wonders for the pacing.
Basically, in the same way I can appreciate the prequels for the story they chose to tell, but see their flaws as movies, that's kind of how I feel about TROS. Admittedly though, TROS has much better acting and personality, etc. There were moments with Rey, Poe and Finn that really worked well for me. It felt really good seeing them all together and made me regret that we didn't get more of it in this trilogy.