I still think the issue is simply that the game allows you to go to such a high level as 36. It unbalances the game, you can't test 35/36 builds and people would rather stop playing than retire when they get bored. Respecing easily at 35 will result in more OP high level builds as you will be able to specialise without worrying about getting bored of the build. People will jump from OP build to OP build rather than stick with something too
Top level should be around 31/32 and then refund people over that level in the form of loom points
I don't think 5lps are going to be easy to acquire in an environment where they become much more valuable, but maybe 6 would be better for 36. LP prices will rise after the initial respec wave that will most likely occur. 6, 4, 3, 2, 1, and free sequentially for 36 and lower. Most people already create optimized builds or are forced into good hybridized builds once they reach that level regardless Most high levels won't be able to afford more than 1 in a reasonable time.
Personally, I'm satisfied with stf. I think that not being able to test certain level 35/36 builds to be a poor excuse, especially since one can simply test individual components for what X ath, wpf, shield, etc. feels like. The only thing you will have to estimate is the increased damage from higher level builds, though, since you'll never be able to reach high PS/PD/PT + high wpf + high ath at the same time. Damage is invisible anyways, so most of the time it's simply perception that's changed.