Thank. You.
This is an example of people taking the amount of time until release for granted, when in reality, anything could happen. Hell, some things might get taken out altogether, changed completely, or end up looking worse. We saw all three with TASM 2, for that matter. There's no guarantees when it comes to things like this.
It's one thing to have faith that the effects team can improve the CGI, but to use that as some sort of argument to dismiss people's opinions is just a presumption that's solely based on wishful thinking. Aside from that, what studio worth their salt would release half-baked visuals in a teaser or trailer that's supposed to be representative of the finished film? That's not just bad business, that's dumb business.
Either way, people should be allowed to speak their mind on what they see in the here and now, good or bad.