You and I have very different definitions of fun.
That we do.
There is zero reason to not allow respecs.
There's plenty of reasons: to create real attachment to your character and the itmes you equip it with, to encourage you to take your leveling and skill points seriously, to give everyone an identical baseline every time there's a new league/race, to prevent people from just making a "fastest leveling" build, then switching it out once you get to maps or whatever to their real build, gaining a considerable advantage over those who don't do that (especially in race formats). And even then let's not forget they
do allow you to respec -a certain number of points, and if you want to respec your whole character you can certainly do that too (you've always had the option) it is just very expensive to do it.
What's the value in leveling a character again instead of just resetting your skill points? What if I want to just try some build to see if I like it/if it's fun? Instead it wants me to either spend hundreds of hours figuring out a great build or just get the min-maxed one from the forums.
Well, yes, the value is committing to a build from early game to end-game. Your build is the skill points you have when you kill Brutus for the first time, and the skill points allocation when you do your first map. Your build is each of the choices you made, including the bandit quests. Your "build" is every step of that process. The value is in the gear and currency you've acquired and knowledge of the game mechanics, farming areas and bosses you've gone through. Yes, spending time with each of your characters is exactly what the game wants you to do. Figuring out stuff over time, not the instant gratification of having your endgame build one and done without going through the leveling process with each character first.
So to me that negates the entire point of their open-ended skill system. Spending more time =/= hardcore. The game should be hard because of mechanics, not because you made a mistake with your character so you might as well throw him out the damn window. I think it's a terrible design philopsophy.
Spending more time absolutely = hardcore. It is like that on games like Dark Souls or roguelikes. It is the very basis of character progression in RPGs; the more time you spend, the more knowledgeable and powerful you become. That is why you lose partial or complete progress if you die. That is why each level during the endgame takes considerably more time than the one before, that is why there are ladders based on getting further and further, spending as much time on a single character as you possibly can. The skills system just gives you the freedom to come up with something new every time, to find a different way if previously you didn't succeed.
Just because you don't like it, it means it's bad design. It is great design actually, one that tests you in ways many other games don't.