that's a good idea. But there's the GM traits too. That said , you could easily boon duration caped with gear and make quickness uptime almost 100% , which will end up in catalyst stack aka more dps nerfs .
if devs want to push this change they should add quickness to sphere specialist ( only for air and keep the boon duration extend) . Meaning : you focus on dps more instead of maintain the boon duration ,when hammer is nerfed more now . And finally , there's a reason why in the other classes they added the quickness in GM traits and not in the middle ones .