Having worked at several startups with large environments where development routinely was leaned upon to jump into production I firmly believe that ideally developers should not install their software (or even touch it) once it is released. Allowing them to do so leads to band-aids, hacks, lack of documentation, short-cuts, and all other manners of badness.
Strictly maintaining that division between development and IT/end users helps ensure that development maintains a complete package. Incumbent in that is that the appropriate feedback loops into development must be established, implemented, and acted upon. Bug reporting, issue tracking, customer feedback, and the like are critical bits of information that cannot be ignored by development.