That's because there are only a couple of guys working on it. Linux has had hundreds of contributors over the years, many of which work for large tech companies like Intel and get paid by their company for their contributions.
I would be fascinated if Hurd could get the same sort of developer momentum to be comparable to Linux. A completely new (as in 1.0 released) and usable FOSS Unix-alike would be quite welcome amongst Linux and the BSD's I think.