Actually, DTrace on Linux is not possible primarily because of the NIH syndrome of the Linux developers. Licensing is secondary - it's not possible to be GPL-uncompatible any more than binary kernel modules (like NVIDIA drivers) are.
Also, note that the whole problem with compatibility is caused by GPL, not CDDL. Sun had two choices - either release the code under GPL, making it pretty much impossible to use by everyone except Linux, or release it under more sane copyleft license that doesn't create additional hurdles for end users. They chose the latter, and I think it was a good choice - even if it was GPL-ed, Linux developers would reject it due to NIH (see e.g. the rubbish about "layering violations").