It always amazes me that someone would shoot down installing modules. On what basis? I have wondered this in the past... point #1 sounds like it's relevant here: why spend company time reinventing the wheel, rather than getting the wheel for free?

ISPs are another story - they don't want to muck about with their environment. So then you're in about point #2 in the above article, even though it referred to university there, the point still stands for ISPs - install to a private directory and just go.