Isn't ability damage and a scaleable standard condition like 'weakened' or something effectively the same thing.
Is there any real difference in saying that you have 8 STR damage, and you are 'Weakened (-4 on all strength related tasks)'. I generally tell players to not recalculate there stats, just apply the appropriate penalty to them. It's effectively as complicated as remembering that they have a standard condition like 'stunned' applied to them.
With Energy Drain I'm more sympathetic to the problems people have simply because Energy Drain is such a complicated condition with such complicated story implications. But ability damage really is usually nothing more than a straight forward standard condition with usually no more lasting of an impact on the story than hit point loss.
Beyond that, ability damage also tends to make an injury feel like an injury, a problem that D&D has in its absence to a real extreme. I use ability damage to simulate everything from insanity, to prolonged sickness to broken legs. It's just an incredibly effective, evocative, and versital tool.
One of the problems with claiming that 3e ability damage is too complicated is that the system that replaced it - large numbers of even more temporary, more frequent, named standard conditions - is if anything even more complicated and is one of the reasons 4e combat doesn't actually run any faster than 3e combat. Not only do you have the problem of tracking the size of penalties to apply, but you have the problem of continually 'recalculating' the sum of these penalties, and remembering that you are in fact penalized and when to remove the penalty. Plus, because the named standard conditions aren't really as evocative as ability damage, the system has tried to replace that lost flexibility and gripping 'realism' by having numerous powers triggered by the presence or absence of the named condition. Without that, much of the feeling of real danger you get from 'save or die' (in 1e) or 'ability drain' (in 3e) is lost. But of course, this mechanic just makes it that much more essential to track everything on a moment by moment basis.
I can understand that you find Con loss to be a real hassle at times, but any dislike of Constitution loss as a mechanic has to be tempered by what you could potentially replace it with. Do you go back to something like 1e where you simply saved or died when clawed by a 3' long centipede, and at any time in the game you were either dead or you were fully healthy? Do you go foward to 4e and track lots and lots of temporary named conditions on a moment by moment basis? Giving up Ability Drain as a mechanic does give you something (all that is lost by the drawbacks of the mechanic), but it also losses you something (all that you gain from it). In my mind, this is a net loss: the pros outweigh the cons.