Updating the graphics drivers is not always possible if you have older hardware. Many people with "legacy" AMD/ATI cards that can not use the newer drivers are having to abandon Firefox because of graphics issues.
This gives the world a clear marching order similar to the one that made everybody realise that an AV and firewall are important prerequisites for a secure web experience: keep your graphics drivers up to date. And this may make OEM computers a couple bucks more expensive.
I really don't get why a browser needs 3D capabilities in the first place. I don't think anybody "needs" WebGL.
Let me quote the word famous statement that Bill Gates never made is a nice analogy about " needs" here:
640K ought to be enough for anybody
That was an interesting read. The writer made a good point comparing Open GL with the apparent more dangerous Active X technology and how that dangerous technology, as stated by Microsoft its self, gets managed to be used in the hostile web environment.