One of the major points for me was how cumbersome the installation process for kernel modules is. Now I can just do make install which works on most Linux distributions.
A kernel module is just a matter of compiling and running `insmod` (or placing it in the correct path). You have to recompile it each time you upgrade your kernel, though.
But seriously, the proper way to do it is a kernel module which you then mainline. I wouldn't be surprised if Valve was to pick it up, since they mainlined some xpad improvements (and the wired version of those controllers)