I'm not sure the dislikes have much to do with the trailer, but most people will see it that way.

There is a lot of people who complain about how "lazy" and poor the editing behind the COD IW trailer is (specially for such a big title). Due to the old and poor animations of the engine, filming the trailer flying around in free cam just makes the game feel outdated and makes it's setting seem even more uninteresting.
Other people like it because it shows more accurately how the game actually is since there isn't any CG and everything is in game.
BF does use a lot of "CG" (or in engine stuff) and parts that seem like gameplay, but in general they certainly did a better job since this IS a "reveal" trailer and you want to WOW people as much as possible. Gameplay can and will always get shown later

For me the COD trailer showed me another COD game with stuff in it, which is good i like linear first person shooter campaigns and COD, the trailer was successful from my point of view but i'm obviously not blown away by it, being mostly gameplay is great for a reveal trailer.
Conversely the BF1 trailer showed me a time period, a time period we're all excited about but there's nothing else in the trailer.
I understand the dislikes coming from people wanting the COD4 remaster to be separate from Infinite and to be feature complete, i'm one of those people, but the COD hate bandwagon chose this game to dump on regardless of its content, instead of airing their opinions the comment section is mostly full of people hoping for new dislike records to be made. "5th Most Disliked video in history LETS MAKE IT 1ST!".
I hope the developers can shut out the stupidity of it.

Undoubtedly most of the negative response are from those that are upset that Modern Warfare Remaster will not be sold separately.

I have to buy CoD:IW for the remaster.

I have to buy BF1