Punished for increased MW skills

There needs to be a solution to this, one of the skills I like most on shileds is the 2 % avoidence however once you get shield masterworking above 50 it becomes very hard to get. Im sure every tree has a complaint like this. please open more slots to choose from after 50 in the last MW skill. If your after the primary rolls and I usually like at least 1, statisticaly my odds are much lower to get them as I level higher