Patrick:
I can see both good and bad in benign neglect (and my experience is limited almost exclusively to daily fee and muni courses, which don't hold the architectural cache of most privates, but is where most golf here in the US is played).
Bad:
-- Overgrown trees, and the lack of money to properly thin trees. Mike McGuire, on another thread re. costing of course changes, indicates it's the equivalent of moving mountains to get his membership at his (private, and very good) club to cut down a tree.
-- Poor bunker maintenance. If you're looking for one place where muni's have really cut back, take a look at their bunkers -- almost all are poorly maintained, with sand rarely replaced, or deepened, and crap (large stones, grass mowings, the like) in them all the time.
-- Lack of attention to poorly draining or poorly grown-in areas of the course, leaving bare patches and grass that doesn't grow back after a wash-out.
-- Greens over time being reduced in size, due to long-time mowing practices.
Good:
-- A big one: no money to really monkey with the course in a substantial way, such as dramatically changing/flattening greens, getting rid of odd and quirky features, or lengthening the course (sometimes due to lack of room, but additional tee boxes are expensive both in the short and long-term).
-- The opportunity for faster and firmer conditions, due to less money spent on "greening up" courses. This is iffy -- I've seen this in some courses, but not in others, where presumably the regulars/super/maitenance staff believe in keeping, by tradition/practice/habit, a green course.
-- No money for other non-related golf expenses (clubhouse expansions, driving range improvements, additional practice areas),which tends to keep what money the course has focused on the golf course. (I'm continually struck by how much wood golf courses buy to expand their clubhouses. Why don't they just cut down the wood they have on the course and use that -- two birds with one stone.
)