You're asking a question that can only really be answered by the developers and decision makers at the companies making the hardware and the drivers.
Ultimately, it can be done but it requires some give on both sides of the fence. Nvidia, for example, claim they could do it but require some relaxation on the licensing of certain libraries.
From AaronP (nvidia staff):
The last time I talked to the
developers working on it, they told me
that the hooks necessary to implement
kernel modesetting were exported to
GPL modules only, and therefore are
not usable by the NVIDIA driver. On
the other hand, that was a while ago
and I haven't looked at it since. If
the kernel developers are willing to
work with us to make kernel
modesetting possible for NVIDIA GPUs,
then we'll look into it.
And again here:
Well, let me rephrase that... it was
specifically designed to be
incompatible with non-GPL drivers, at
least according to Dave Airlie when I
asked him about it a couple of months
ago. I haven't actually looked at the
code, myself.
That was two years ago... So no, this hasn't been moving along particularly fast. I fear there's probably more luck in getting X loaded up faster and just using XSplash.
But when you look at it from Nvidia's point of view, what does this feature really add for their users? Would they benefit more from 400 man-hours going into Xorg development or 400 hours going into making the boot sequence more pretty?