Several contradictory things are simultaneously true:
1. Maduro was an oppressive, unpopular and illegitimate ruler, disastrous for his country and the region.
2. Using the US to remove him may have been equally illegitimate.
3. Venezuela would be better off with a new government under the opposition's Edmundo Gonzalez (who probably won the presidential election but is now exiled).
4. It's not clear that Maduro will be replaced by Gonzalez. Maduro's VP is still apparently in power, as are other regime figures and the Cubans who back them.
5. As we've seen in Iraq and Libya, it can be easier to topple a leader than to establish a new government; sometimes you get a worse leader, or Somalia-style chaos.