I was reading System Performance Tuning, 2nd ed earlier. Your post reminds me of the following section:

The most powerful tool available to you in order to control the workloads on your systems is user education. Enforcing strict CPU time or disk quotas, while effective, often adds to a "resentment of the mystery" phenomenon. This leaves users feeling rather like medieval serfs: there are certain things they just can't do, like encourage the rain in a dry season, and all they can do is go and beg some rather mysterious people who usually live in caves to try and fix the problem for them. The end result is that the users get very frustrated.

A much better solution is to explain the problem to your users, how their actions induce it, and the solution to the problem. Many times, this sort of forthright discussion will produce the results you'd like, with much less of a headache.

I thought that summed it up rather nicely. Educate your users/customers and you'll save yourself a lot of trouble and improve the arrangement for all involved parties. Consider their position/mindset before you react.

The book also contains lots of excellent information on (you guessed it!) System Performance Tuning :).