Balance
You may be right, but in the current status, it has to be done carefully.
Indeed, one thing you forgot about the frequency is balance fixes lead to a quick discover of “meta/cheese” builds that use synergies in the new set of skills/traits etc. which eventually makes them better than current “meta/cheese” builds that will be nerfed.
So, you can be sure that as soon as a balance patch is out, there’s a wall of “plz nerf this !” from people who have been nerfed and are failing against builds that have been bossted. Or threads “okay, ANet decided to kill put profession or meta here”.
In a nutshell : there’s an adaptation time so that people will get the fixes, agree they’ll have to deal with it, may think of new builds if they want to change, test them and get used to them. And this is how a new meta blooms.
On another hand, increasing the frequency may be a way to “keep things blurred”, hence prevent the meta/cheese trend. And so, work for diversity.
It has to be thought of.