Fact (because I say so): TBC > Cata > Legion > ShaLa > MoP > DF > BfA > WoD = WotLK
My pet collection --> http://www.warcraftpets.com/collection/FuxieDK/
As long as those trailers are made with game graphics, i'm perfectly fine with them not releasing them.
I wouldn't mind a trailer as I'm currently not any hyped at all.