It is kind of boring as a caster tbh. Our strength and dex never matter (because we cannot hit shit, even when those are high, I've tried), our stamina is capable of hitting the 400 range, and our agility even hits the cap before hidden strength is applied, and even a bit beyond. Those two are granted something to look at, though not extremely important. But the things that have the most value for us, cha and int, get capped really really really fucking fast. It's entirely possible to hit the int cap as a mage around potorment (if one is a bit short, one pops fireform). This was a few years ago, and droppable loot has drastically improved, so I'm thinking it may be possible sooner.
Charisma doesn't hit the hs cap for a while granted, but in the high end it's not uncommon to see people who are 70-80 above the cap, with nothing to show for it. Casters at the high end pay more attention to melee stats than two of the ones that should be most important for them.
This is one of the reasons playing a caster is fuck all boring.
But I'm rambling a bit. In short to answer some of the points brought up.
"INT and WIS are affected by HS" Yes, very yes.
There are alot of ways to do it. Really I don't think even giving the original values is going to mess things up all that much. Though personally what I'd like to see is this
INT past cap=> Helps energy/defense, small amount of mana for int casters.
Wis past cap=> Helps resists, small amount of mana for wis casters.
In addition I'd like to see earlier bonuses for these as well. Way back when when charisma was changed, no one wanted to see a garbage stat. Well, we still have garbage stats. Consider
INT/WIS both worthless for
Warrior
Monk
Rogue
INT worthless for
Cleric
Shaman
Druid
Ranger
Paladin
Beastlord
Wis worthless for
Mage
Enchanter
Necro
Wizard
Shadowknight
Bard
each is worthless for 9/15 classes. It would be nice if that was not the case. Nor do I think it would be particularly unbalancing.
"Wouldn't raising this limit also had an adverse affect of making it easier in the higher end raids?"
Not really. You've got to consider the amount here. If you do in fact have 500 stamina, you're about 15 over the hidden strength cap. That's not a whole hell of alot. Say it's 30 points over, essentially the same benefit as 10 regular points. I doubt it would change things all that significantly. Not nearly to the extent tomes will and have for instance.
"unbalancing"
No. Just no. Really. Do you have any idea what spells actually cost? Any? At all? Healers granted have an easier time of it, getting more casts with the same amount of mana, but unbalancing casters would be pretty much fucking impossible with just adding mana. 1 rain costs like 480. That's a fucking lot. Quite alot. Wizards don't have it easy there either. If hs was adding something in line with nwaijs suggestion like 1 mana per point over cap, it still wouldn't be enough to cast another full spell with close to the most optimized possible gear setup, for a mage at least (one of the more mana efficient caster classes). At best you're talking maybe a good 200 points of mana at the extreme high end (if you're really really trying to get it over cap, also if we're following the regular hs model, you're going to get about 130 out of it max).
After a certain point you can sit there and chaincast for 20 fucking minutes, regardless of class. adding an extra 20 seconds isn't going to change things all that significantly, but it is stupid to have a stat that caps in like tier 3-4, and just keeps going up with no benefit all the way to max tier.