This is not the general consensus, quite the opposite in fact. A key problem with the original dungeon keeper was a lack in content where a large part of the original campaign was tutorial and introduction levels. Most people find very little challenge in the original campaign. KeeperFX has lots of user made content bundled, and much more available for download, but most of this is a significant step up in difficulty compared to the original game, although easier stuff does exist. There's also a computer assistant that will help you play (build rooms for you, drop units into fights for you), and you can configure the game to play at a lower speed so you have more time to react or plan.

Yes, I don't have much experience or skill, but there's also some old dependencies that prevent a linux port at this time. DK2 was the game with the early 3d models, DK1 is all sprites and so in my view has held up quite well graphically because of that.