"Oh, I just upgraded this package, yeah, can you put that in our master image?" sigh
Do it right, and you can get the developers all the info they need without having access to the box itself. Not only that, but you make it easy to spool up new dev environments for new employees.
If access does need to be granted today, then thought should be put in to see if that can be avoided tomorrow. Need a tcpdump today? Great. Access granted. Tomorrow, I'll have a script for you that takes a tcpdump and puts the file where you can access it. Access revoked.