I think the main problem with how the Business model is badly perceived by new players come from 2 points : Inventory frustration + Front-loaded cash shop
I know that the current inventory is manageable, I played like that in closed beta, it was okay.
But new players don't have the knowledge that we do, they hoard plenty of useless items, don't know what to throw, what to sell, what to keep.
The result is that by the time they reach T2 / T3 they are struggling with inventory, scrapping for every slot, feeling like they have to leave useful items behind because they can't carry them
That's when the second point come into play.
Front-loaded Cash shop
What do I mean by front-loaded cash shop ? Well, it's everywhere ! I think almost every screen (Inventory, Vault, Auction house, Craftsman, ...) has a shortcut in it that lead to the Cash shop or spending Electrum.
I don't think it's a problem in itself, I even think it's just good user interface. (And removing these shortcuts to just put everything into the store would just feel like hiding the dust under the carpet tbh)
The problem is that new player are already frustrated with the inventory, and everywhere they look in the game they see the cash shop.
It feels like a set up, like the game tries to force them to purchase more inventory while not giving them enough to work with from the beginning : It feels like a cash grab.
What to do ?
Educating new players on inventory management(what to keep / sell / throw) is not enough, most of them will never set foot in the forums and even less on the discord.
I don't really like to tell people how to handle their business model, I don't want freebies (we already had a few) I already purchased an inventory / vault size I'm comfortable with.
But right now new players feel frustrated playing the game, and you should never feel frustrated playing a video game (at least not continuously).
So what to do to relieve that frustration ? my take on it
Inventory start to become an issue for new players around T2/T3, that's when they start looking around and only see the cash shop.
Give them something else to look at : I propose a quest (poping up after killing the T2 or T3 boss for the first time) from the Craftsman or another NPC, retrieve some T1/T2/T3 component for him and he will reward you with a +10 vault upgrade.
In the late game, have another +10 vault upgrade behind a late game / early late game achievement (maybe killing all the normal bosses ? or all the hard bosses for more late game)
This will push the Vault to 40 slot, which I think is a good spot for it.
It will still feel a little restrictive in the late game (charms and imprint start to take inventory slots, high level equipment start to become more valuable) but not enough to be frustrating.
I also think a third character slot could be good, It could be earned after dying in the well with each of the 6 classes for exemple.
One last point, it has nothing to do with the business model. It's about communication.
You are one of the most communicative Dev team I've seen but ... Right now your communication is not that visible to new players.
A lot of new players won't come here or on the discord, their first stop will be steam and the steam forums. Some more interested users will eventually go to Reddit and right now your communication on steam forums and reddit is very light.
I know that the whole team is very busy squashing bugs, fixing servers and other problems but presence on these media is required right now.
When new players see a lot of cash shop, a lot of servers problems (registration, downtime, rollback) and no >visible< communication from the dev team, it contribute to make the game feel like a cash grab for them, like you don't care.
It could be some pinned post on steam / reddit : a roadmap for them to see what is coming in the future, a post linking to Discord and the Official forums, a post acknowledging the current problems with the servers or the game, ...