tremere110: One of the reasons I love Tales of Maj'Eyal is the limited respec. You can unlearn you most recent points while you try new stuff and figure out your focus but it becomes permanent once your character progresses and becomes more committed to their techniques. You do have the option of full respec in exploration mode though.
I guess if I decide to play that game, I'll likely play in exploration mode; it sounds like it would be fun for someone who loves to experiment as much as I do.
The question is, are there any differences that would affect the results of experiments? (I mention this because, in Nethack's wizard mode, wishes work differently, so it's not suitable for testing the limits of wishes.)
Sarisio: I don't like respecs, but personally I like when RPGs (I don't limit this just to ARPGs) have very high level caps and allow you to master all or nearly all skills if you want so, given enough time and devotion. That's why I like Final Fantasy X, like Final Fantasy XII PS2 English version (and dislike IZJS version), Agarest games, etc.
On other hand, I don't like when max level characters have access only to 10% of available skills. Player should be given a choice/option to level up to very high levels, raise all stats to their max and all skills to their max.
Interestingly, I am sort of the other way around here. I prefer when characters are realistically limited in power, but respecing is something that can be done as easily as job/ability changes in Final Fantasy 5. In other words, I prefer it when I can change my setup anytime outside of battle I feel like doing so.
On the other hand, I am playing Torneko: The Last Hope, and when playing as a Warrior, you do have to make irreversible (for the current dungeon run) decisions about which skills to set on your equipment; however, because these dungeons are not individually as long as full-length RPGs, and your skills reset to unassigned when you leave the dungeon (as does your level), it doesn't bother me. (In case you are wondering, it is possible to reach high levels, but there is a (rather high) turn limit on each floor, and there is a starvation mechanic.)
Starmaker: Depending on the game (not even on the genre but on the precise mechanics and the strength of counters), respeccing can make the game ridiculously easy and even pointless; other times it's like preparing a different set of spells with a D&D wizard.
It is for this reason that games need to be balanced with all their decisions in mind. If you are going to allow anytime respec, balance the game with that in mind. (Final Fantasy 5 does this well.) This also applies to mechanics like the save system (save anywhere should be balanced appropriately, but don't force the player to do too much reloading, because that gets annoying), the rest anywhere mechanic (common in WRPGs, but almost nonexistent in JRPGs), health regen (for those who consider this to be a modern mechanic that cheapens the gameplay, I could point out that this mechanic was present in Rogue, which is neither modern nor easy), weapon durability, hunger, and pretty much any other mechanic. (As for weapon durability and hunger, either make sure the mechanic matters or don't include the mechanic in the first place.)