The huge patches were a result of how steam can only(at the time), update content at the file level, and even minor updates to an unreal engine game results in large files changing, since most things are packaged together. A while back the game required converting to a 'new' steam format, which was so that binary diff sort of patches could be distributed rather than downloading entire files fresh.
I agree the game is fun, but it got old when my gear could only support my doing 2 levels of nightmare difficulty(ramparts and spires), and even that was snatched away when they patched in the stupidass sharken characters that push your shit out of the way. Now I'm relegated to not being able to do nightmare myself, so the game is effectively identical to Diablo 3 and the auction house, where you have to farm money and buy high level items from other players, and that's not fun at all. I can still get some enjoyment from helping other players tackle the nightmare challenges and giving away reward weapons and stuff, but it's annoying that the end game has such a huge progression stomping wall.