Anything that makes the server harder is probably a bad idea, as I don't think anyone (at least not anyone who isn't pretty high level) thinks this server is too easy. Rather than continuing to make it a place that is less and less attractive to new blood, it would be preferable if developers put their limited energy into some of the many "nice" things players have asked for.
Regarding the specific of a constitution drain, that is less of a penalty, for example, in settings in which it is easier to boost one's ability scores than here. Moreover, it actually penalizes a beginning character worse than a high level because XP can be recouped. Ability scores cannot.
The XP penalty already exists as an option...for those who want to take it and think it is the "right" way to play. Making it mandatory, therefore, would be reducing player choice and imposing the preference of one group of players on another.