^Conquest was how people built nations back then, and thus you could say that pretty much every imperial ruler committed evils by our standards (considering that they were undemocratic monarchs, usually kept slaves, etc.). Morality has advanced so far in modern times that even the best people in the past would be pretty rotten people by today's standards.
Timur was much like Alexander or Genghis and many other imperial rulers: using brutality to create his empire, but then using the unity and stability of his empire to foster notable advances in art and culture, the study of history, mathematics, astronomy, economics, etc. If not for the progress achieved under empires like the Timurids and il-Khans, Europe would never have adopted Arabic numerals and the zero, and Copernicus would never have solved the riddle of planetary motion.
This is the paradox of the ancient world, that so much progress and enlightenment went hand in hand with such brutish violence. It's what I've been saying, that you can't understand history by reducing it to some cartoon battle of good and evil.
For the Wikipedia article to say Timur has a "predominantly barbaric legacy" is inexcusably biased; a statement so judgmental should never be permitted in a scholarly article. The downside of Wikipedia is that anyone with an axe to grind can rewrite an article to replace fact with propaganda. The upside, though, is that anyone can fix it.