That term used to mean something. Players would be following info on MMORPGs and when they announced "beta testing", many flocked to be lucky enough to get picked. Usually, it was near release (actual BETA step) and most of it was just server load testing. It was not "fun" for most, but players got a "preview" of the game.
Now, "beta testing" is more likely "alpha testing", with quite a bit of time before release. It's also purchasable, many times as a pre-order.
Do you recall the first game you got lucky enough to beta test?
Mine was Dungeons & Dragons Online. I recall being so hyped up for that! The game disillusioned me, though. It "vaguely resembled" the tabletop game I wanted. i realize much of it needed to be "video gamified" in order to attract players, though. Who wants to play a spell caster that gets to start off with just one spell each day.
The last game I beta tested was ES:O. After that disillusionment, I have stopped beta testing and just wait for actual releases
Again, do you recall your first beta test for an MMO?
Personally the only modern MMORPG trend that annoys me is the idea that MMOs need to be designed in a way to attract people who don't actually like MMOs. Which to me makes about as much sense as someone trying to figure out a way to get vegetarians to eat at their steakhouse.
(And now Burger King has MEATLESS burgers!)