Read through an interesting article on MMORPG.com and was rather surprised how very uninterested the Elder Scrolls Online community was to help test out the game. Whenever I play an MMORPG, there's always been a group of players that are eager to help test the game, whether it's pay-to-play or not. I mean, if you've already invested in the game to make your characters, wouldn't you also be invested in keeping those characters viable by helping test new content? I guess if a MMORPG's community is not invested enough in the game, then they wouldn't be invested in helping that game grow with or without bribery.
On the one hand, if a MMORPG doesn't offer a test server, then players would expect the developers to test the game well. On the same note, the more invested players would insist on having a test server so that they can provide solid feedback on new content before it hits the live server.
On the other hand, if a MMORPG does offer a test server, then more pressure is on the developers to deliver on player suggestions as well as more pressure on the players to give decent feedback on test content. This option provides a better dialogue between the developers and the players if the players are invested in helping the game get better. Otherwise, if you have an entitled playerbase like what ESO has, then the test server is likely to collect dust.