An architecture is superior for a given purpose, or judged by a particular standard. There isn't some magic score card which can declare an architecture to be plainly superior.
HURD will be clean. Plan9 was clean (and I have a fondness for it). I also prototype some logic in Haskell but know full well why most production code isn't written in it.
Linux is a bit of a mess. So is BSD. So is every general purpose operating system that has ever been fielded for a significant period. The warts come from being adapted to serve many different purposes, and working around many real world problems that clean-room architecture gets to just ignore. And getting some of it wrong and only fixing some of it halfway because it turns out that in real deployments (not just "the market"), clean isn't the most important thing people need from an OS.
Building a fresh OS, even over two decades, is impressive. Most Slashdotters couldn't do it. But, seriously, many research OS's have been written and shelved since HURD was started, and none of them have run around insisting they were the second coming. HURD has some neat ideas. But it's getting mocked because it's been presented with the kind of pretension and arrogance you only get away with if you deliver perfectly and on time.