I suppose a big benefit is just not having to worry about it. I think in practice that's one of the most common reason to leave things be. Any change will create enemies within, might lead to worse outcomes, and will cost significant work.
I've been in a number of situations where a 'bad' manager remained while new upper management was busy with 'an entirely new approach' and changing things left and right. In one case, I had the luck of being a good friend of someone in upper management, so I could discuss this issue. This manager indicated that he was well aware of the problem, but he explained that it simply wasn't worth the trouble to deal with this 'bad' manager right now, for pretty much the reasons I mentioned above.
Of course, 'right now' remained the argument, since there were always more important things to do. For all I know the guy's still there, or maybe even promoted.
Hell, come to think of it, it's very much like the code I work with. Significant chunks are a mess, but there never seems to be time to refactor. New features and 'big changes' always take priority, and somehow the big changes rarely impact that shitty code, so it stays. I'm not sure if that's coincidental.
tl;dr: apparently refactoring is avoided in most (bureaucratic) human endeavors.