quick spear, highest landrate debuff in game with shocking 130% base landrate, its 900 range, its AoE, can crit. now when you apply all the protecting buffs and stats from armor (not counting puri), it goes to something around ~40%, which is still INSANE number for AoE stun debuff on max range, with puri it goes around ~10% landrate, which is not that good, but also not pathetically low (imagine mass fights where people are kiting, if you land quickspear on 10 people and you manage to land it on 1-2 people who get left behind and killed, its huge bonus)
now they got added new custom skill, which increases landrate of stuns by 30%, now does it help when enemy has puri? well, not that much, but you also have to consider what if the fights go longer than puri lasts, if you want to have decent landrate of 20-30% on quick spear with puri, does it mean you will stun 80-90% when puri goes off? isnt that a bit ridiculous to think that after 2 mins of fight, ANY warlord without epics will go, toss quick spear and stun 8-9 ppl out of 10?
next thing you say about damage, that damage never goes more than 1k, except if crits, boi, you realize 1k is decent amount of damage, especially considering all your skills are AOE? that means if you go inside of people and do 1k damage to 10 people, thats 10k damage from 1 skill, damage dealers would dream about such damage, on top of that half of the skills apply stun/hex effect, you can use provoke which goes through puri (i think) to further increase your damage
all in all, increasing % on stuns would totally unbalance it the moment there is no puri on table/when it fades, increasing damage on AoE CC char makes also no sense, you are not supposed to be DD, defenses being low, sure, imagine if they were high and you were 20-25k CP+HP punching bag, would be better at tanking than actual tanks, only thing you could pray of is rebalancing puri song - being it more constant but having lower impact (aka having reuse equal to duration, so you can perma have it on, but lowering 80% debuff resistance to like 50% or so, which would give chances for debuffs to actually land with decent, but not OP percentage)