So glad you had a bug free experience all the way to tier 7 haha!
All your points are incredibly valid, I will be addressing all of them in future builds.
There will be way more abilities and nodes in the ability tree, currently it gives you a sneak peek of it's intended final size as you move around.
And the intention is definitely to make the tier progression considerably harder, as those will each have their own quests and content. I want you to spend at least 45 minutes in each tier, and more on the higher ones. It will be balanced to force you to optimize your gear and build as you go, don't want you one shotting tier 6 with your tier 4 gear and no resets for example.
As for the respawn system, it will eventually cost gold and if you can't afford it you'll respawn in a safe area instead of on the same spot. So you can't afk while dying constantly. That should fix it!
Thank you so much for playing and the detailed comment, really appreciated! Obrigado!