Because that makes your software not just proprietary but _hugely_ proprietary (remember, even GPL software has absolutely no conditions on _use_, deliberately).

Come to think of it, it's not even clear you could effectively write such a license for software (the analogous artistic license is generally about performance/broadcast, which doesn't have an equivalent in software). Once the user has received the code from the licensor, legally the situation is out of the licensor's hands _except for the issue of redistribution_, which is what the GPL restricts.