I would say that players that don’t play the Beta or just play it a few minutes and then stop (Didn’t like the game or were just using it to push their viewers in Twitch.tv) should be the people that should be taken away their opportunities to play.
The reason is that first of all some people might not understand when something is not working as intended or in other words “A bug”. Some bugs are obvious and easy to see and report, but some are not as common or as easy to detect.
Also the more players you have testing the more you can test the stability of the servers, maybe something in the translation deparment didn’t make much sense, or maybe there’s a zone/map that drops your fps. The more players you have the more likely you will find bugs but at the same time the more likely you can detect things that even thou are not “Broken” are not working as they should (Example could be broken classes or doing too much damage, some classes early game been horrible, etc).
All in all betas are meant to test multiple things and rarely are there for you to “Find the bugs”, that’s why we have Alphas. More than not Betas are use to test server stability, to see how people react to lets say to the ingame store and prices, etc. As a beta tester there are way more things for you to test and report than just bugs (Exploits sometimes are as bad or even worse than bugs)