A lot of words have been used to describe La La Land. Among them, two of the most prevalent I've seen are "wish fulfillment" and "escapism". I understand why people give the film these labels; The visuals are colorful and vibrant, the music is whimsical and and romantic, and the lead couple is charming and archetypal. But to call this film an "escape" from reality, or in a more negative sense, a "misrepresentation" of reality, is, I think, a simplistic and surface level view of the film, and very very far from the heart of the story.
La La Land isn't a fairy tale. It isn't about dreams coming true (at least not one-sidedly so). La La Land is about the tension between dreams and reality, between what we want and what we're capable of getting, between ambition and practicality. Stylistically, the film embodies this wholeheartedly- the old fashioned "Song and dance" vibe is consistently and intentionally undercut by moments of contemporary realism- both tones exist, weaved together throughout the film, in tension yet not separate.
If no other moment could "definitively" demonstrate this, then look at the ending; Mia and Sebastian find the success they dreamed for, but at a cost. They lose each other, and in their collective dream sequence finale they imagine what would have happened if they had been more perfect people, people like in those old movies, who knew exactly what to say and do at the right moment, and existed in a cleaner, purer reality where things work out the way they should. But that's not the world that La La Land exists in. La La Land exists in a world of tension and compromise (much like Sebastian speaks about jazz earlier in the film). So in the end, a smile must suffice. This goes so much further than "becoming a movie star" or "getting financial success"; this is a truth that everyone has to deal with, no matter their path. We all have dreams, and we all have to weigh those dreams against the bounds of reality, and we all have to navigate the narrow space between.
I'm sure this is "no duh" for most of you, but I've seen so many people (even professional reviewers) come away with totally far-off takes that don't really do the film justice. La La Land is a great movie, and in my mind it deserves every bit of praise that's coming it's way. For me, it's actually my favorite kind of movie; a movie that acknowledges (and embraces) the flaws of reality without excess of cynicism. That's a tension in which we should all live our lives.
TL;DR La La Land is not about wish-fulfillment or escapism; it's about the tension between ambition and reality, and the inevitability of compromise in turning those ambitions into reality.