I agree with a lot of the points people have already said but I wanted to include one more thing. 1.8 is really easy to get into (just point at the enemy and spam click) but really hard to get really good at (ie: butterfly/ jitter) and I think this is the perferred skill progression for most players. Compare this to 1.9, which has many more variables and concepts which make it harder to start (shield, attack speed, axe, crystals, etc) but once your good at it itβs pretty easy to improve.
TLDR:
1.8 easy to pickup, hard to master
1.9 hard to pickup, easier to master