I won't say you're wrong because you aren't, in fact the system works very well also with non-rt kernels. But the graphical stack is not really designed like the average linux stack, the BeOS is somewhat hungry in terms of timing and I believe our implementation can take advantage of a RT kernel. But if it'd proven unnecessary I'd be 100% for changing it back, it's just a package in our image creation code after all, we don't strictly depend on it.