It All Just Feels Miserable ... Why?

The game seem fine during the campaign. Reasonable progress in skill points, gem upgrades, item upgrades...

In the end-game you need item upgrades, but these are way too rare. Recombinator sucks, crafting materials are rare and monster drops are 99,9% unusable garbage... not event worth to pick up. It is very likely that you hit a 'wall'.

GGG balances itemization around the trade market and this is sad. Trading is not playing the game...

+1 Agreed