1.) "It's just a movie." Sure it is. But that doesn't mean I can't say "I dunno...smells like a turd to me..." Besides, we all came here because of our enjoyment of "just" a movie so much so that we wanted to own our little piece(s) of said movie(s). "Just" a movie is "just" a tired defense to me.
2.) "You should give it a chance!" Well hey, if I could "try before I buy", I'd be happy to give it a chance! Sadly, you don't get to walk out of a theater and say "That sucked. Gimme my money back." When they start doing that, I'll be happy to give more films the benefit of the doubt. Until then, I'm gonna be a discriminating consumer and err on the side of saving myself $10 and 2-ish hours of time.
3.) And while it hasn't been raised yet..."Oh yeah?! Well YOU go make a movie!" I don't need to be a master chef to know when I don't like the taste of my food. BY the same token, I don't need to be a filmmaker to know when I don't like the look of a movie.
Look, I get that some folks dig what's in the trailer here. That's awesome. I actually kind of envy you and your optimism or your ability to enjoy this kind of stuff. I have a MUCH harder time just "switching my brain off" or whathaveyou and enjoying a film, especially when the source material is something as entertaining (to me, anyway) as the GL universe.
I'm a really picky customer who has been, over the last decade, consistently disappointed by films whose trailers looked "AWESOME!!!", to the point where I now no longer trust trailers. Moreover, I don't trust Hollywood in general to make the movies I want to see. I don't think I'm their demographic anymore, at least not for big-budget action-sci-fi-adventure films. They're selling to someone else. Maybe you. Lucky you, if that's true. But yeah, I can't "just enjoy it" any more than I could "just enjoy" eating what tasted to me like a dry, grey, overcooked cut of meat. I'd be especially disappointed if I knew it was a particularly succulent cut of meat from which all flavor and richness had somehow been drained by the preparation and presentation.
Knowing this about myself, I'm increasingly skeptical of films in this genre because, based on my experiences, they frequently disappoint or underwhelm me.
Rock on if it looks cool to you, though.