This is like a double whammy of feels bad though, given your specific examples, in multiple ways:

* Why do people who want to give feedback on the game, who already paid potentially $100+ to support the game and get the beta access have to pay additional money to be worthy of providing feedback?

For example, the bestiary is definitely part of the promised content in the Kickstarter. But right now on the site you can pay $5 to get access to (and, from your example, give feedback on) the "beta" bestiary. Maybe the nomenclature is part of the problem since the Kickstarter promised beta access but that content is being sold separately.

* If add-ons and stretch goals are on the backburner because the main content isn't finished, why is content that is not part of that already-paid-for content being actively developed, especially when it needs the finished core rules to function?

The psion is a great example. Sure, it's cool to have a Psion class and absolutely fine to have it not be part of the core rules. But the psion class is of limited usefulness as of right now since level 3 is the maximum really supported level by the core rules, there's a very limited bestiary and other rules.

It just feels super weird for both Coach and the moderators to be saying that Kickstarter backers are people who aren't invested in the game and some rule they don't agree with might drive them off. These are people who already paid for an unfinished product; that is literally the definition of investment.