You explained how the bunt can be used as a weapon just fine, and I agree with using it as a tactical weapon, but if it doesn't really work that well in college then why the hell do they keep doing it often to excess? I think I saw 4 or 5 batters in a row do it in one game. Then they actually let some poor girl swing away, then they kept right on with the shitty bunts.
Well I won't try to explain the psyche of every coach as to why they do something, but there's obvious implications as to why they do it.
1) They are used to doing it. A lot of these girls are taught this in High School and even in College and use it with some success at the lower levels. When you get to the highest levels of softball it doesn't work, but that doesn't mean you just abandon it. It might still be the best chance at getting on base for some of them. Have you watched some of them when they swing away? Against a top pitcher, it can be embarrasing.
2) You got to keep the infielders/pitcher honest. If you don't at least attempt a bunt from time to time the infield will play deeper and it's even harder to get a well hit ball through the infield. A lot of those "attempts" are really just there to open up the holes for when you do swing away.