Am I the only one who finds it kind of lazy when they use the Music from other movies instead of using their movie's own soundtrack.

Eh, it happens all the time. Usually they just do it because the composer hasn't put anything together yet (and why would they, just for a teaser trailer?). Or just because the other music sounds better.

The trailer heavily reminded me of a Terrence Malick movie. No idea if the final project will be that way, though.

I know it happens, it just bugs me, especially when ripping off really famous soundtracks like LoTR.