2) Skill trees are so linear so every build gets everything it needs in a short time (You can reach lvl 21-22 in act 1 already. So you only need 2-3 more levels to play the build as it's intended already.) I think it also had to do with balance reasons in the first few versions of that mod. Though early game balance isn't very good atm.
- Many people are waiting only for sigma and don't even bat an eye that there's a new ladder again.
- There were basically 0 changes to builds this ladder, so there's no motivation to try out something new for the vets
- Mainly the vets already have tried out almost all if not all items in the game at some point in their gaming experience, so those people aren't.
--> This seasons is rather meant for new players, who usually struggled with finding everything. However, since there weren't any changes, there isn't much to try out. Plus 1/3 of all SU's will be removed in the next patch(es) and others will be replaced/reworked, so this whole "Try out every item" thing isn't really worth it since we don't know on which items we can still count in sigma.
4) Early game: No. Late game: It's not as bad as in early game, but there is undeniably a huge difference between some builds. Some are easier, some are harder, but all in all every class can do every uber in the game. You just have to switch builds for some ubers eventually.
5) Holy Paladin (Either meele or caster), Thronwarden, Trap rat, Summoner Barb, Aerial's barb (look in the guide section), Scorpion blade assa, Castersin.