By all means, put as much pressure on these companies as you can. Every
little bit helps get the message out. But for volunteer programmers to make a
suitable driver for highly complex chipsets that aren't even documented is
impossible. Releasing free software drivers without any blobs is AMD's and
NVidia's responsibility, and they fall short of it.
PlaneShift is an example of a fairly ambitious 3D MMORPG (still in alpha,
though) for Unix-like systems. Unfortunately, only its engine is free. They
made an unfortunate decision by deciding to keep all the content under a
separate proprietary license (under the fallacy that it will lead to forks
and artists won't want to contribute content if it can end up being reused,
which the Nexuiz project would find laughable).
But if you want to work on a free software MMORPG, please don't let the
driver conundrum our community faces discourage you. The PlaneShift engine,
which is a modified Crystal Space engine and is very cross-platform, should
be able to do whatever you wish for that type of game.