Wow, long topic @__@
Well, first of all, I really don't think there's much wrong with the fighters. Out of the four classes, I think they are easily the most balanced. Maybe not the best, but they are pretty well off.
Clerics aren't overpowered nor underpowered. I think though that they should be given something to live for lvl 60+, since I've been seeing that a lot of 60+ clerics are complaining that they're the same as a lvl 49 cleric with the same skills and they leech off more damage. If there's some better skill in BK that's not in Fiesta right now, it should be implemented after lvl 60, or else people will want to quit.
Mages I think already have a very good start. I really don't think they should be given stun. With a little bit of empowerment on their fear they could have 5 seconds (?) of stun, which could be good enough to kill an enemy with their high damage. I think that they're fine the way they are, and I've even heard of mage tanks. They are slightly on the overpowered side in my opinion.
At my level, I don't feel the pains of all the weaknesses of archers. I don't blame the weakness of no AoE skills for the lack of archer-wants, I think that when Burning Rock is opened more people would want archers again. The main reason for AoEs is because it's easier to gain exp because the mobs are easier for them, as there are no more harder mobs. When the mobs are harder in BR, archers might be more accepted in party-vs-one-mobs'. What I think we would need is an evasion/aim buff, or a walking skill buff.
I don't find class balance to be that big of an issue from my perspective, but apparently it gets worse and worse the higher leveled you get.