Previews don't really ruin anything for me... it normally turns out like in the case of crossroad where the preview was underwhelming and then the full HQ completely blows me away. It doesn't always happen but most of the time it does and I like that feeling.
Just listened to the previews and honestly, I have no idea what the hate is all about. lol
Thank U sounds so sweet and uplifting... like the MY ALL and HONEY kind that I like. It doesn't sound Momosu or H!P-ish at all (and I say that as a H!P fan), it's sounds like a happy ASFXX era Ayu to me.
insomnia sounds so dark, and cool, and awesome... everything I hoped... why is this an interlude?! T__T
sending mail is the only one that I'm not sure about. It's the most "anime-ish" of the three, like truehappiness said the start definitely gives off vibes of a catchy opening theme. But because of the LQ I can't really get a grasp on the intrumentals, which I suspect are pretty good. The chorus makes me think of a mix between Two Mix's "Just Communication" and Namie's "BODY FEELS EXIT".... both of which I love so definitely looking forward to hearing this is full HQ.