It's really just a round and round debate between the fans who are upset for lack of past characters (and other changes) and the fans who are in full swing on everything shown so far. It's also pointless to keep discussing it when others have an 'I'm right and you're wrong' mentality.
No one is saying that a zombie apocalypse can't involve other characters- of course something like that would drag many different lives into the mix. But the game series has always involved the same iconic characters, as
@Spikeyroxas listed, and that is the perspective we are coming from.
Not saying that the new characters won't be likeable- because they just might be once we all get to actually play this game. But understand that this is a
big change. I'm sure the bulk of the fanbase didn't rush out for RE6 because of characters like Helena or Piers (though they did establish their own fanbase after the game was released).
But maybe this game will give Capcom a chance to focus on what they want to do next with characters like Chris and Leon because those two have a lot of unfinished business since RE6.
As far as 'YouTube' likes are concerned, I really don't think that that is even a good way to base the stats of what fans are thinking and liking with the trailers. I personally haven't hit the 'thumbs down' button for anything yet because it is all up in the air still and I'm going to give the game a try despite having changes that I know I don't care for.
That all said:
The healing animation looks cool and it's nice to see that there is going to be an item management box.