The purpose of Early Access is to gather as much information and feedback as they can.
In addition to the Forums they also check Reddit, and supposedly Steam (though from what I've seen in Steam I wouldn't blame them for avoiding it completely). There is a Feedback option in the launcher for the game though. I think they've given people a more than adequate number of ways to provide feedback, though I do hope that a lot of the people who bought into early access are using their time to let their thoughts be known.
The truth is though that the people who are more passionate about the game are going to post more, and their opinions may differ from yours. Really people aren't reviewing one game here, but four, all depending on what they want out of this title, whether that be
- A DoS game with D&D flavor
- An exact replica of Baldur's Gate 1/2
- A one hundred percent faithful adaptation of 5e
- As close to 5e as they can get while still understanding that some changes will be made adapting this to a video game
From what I've seen looking through here as well as Reddit I see most of these groups being fairly vocal, and typically the most vocal group wins. It's also going to be impossible to one hundred percent please any of those groups, and there will obviously have to be some compromises on the way to release.
I definitely hope that as many people as possible make their voices heard though. It'll be exciting to see what the final version of the game ends up looking like.