High SPLs cause your ears to form wax in an attempt to counteract the assault they are experiencing.
In the popular music and much of motion picture sound industry, high SPLs are inevitable, so you will inevitably experience hearing loss if you stay in the business long enough. I know many middle age film mixers who have chronic tinitus and a big hole in the high mid range and a roll off on everything over 6kHz. The same is true of many music engineers, probably even worse. They also have trouble understanding people talking when there is any background noise. This is a consequence of permanent hearing damage resulting from constant exposure to high SPLs.
When you hear other people's mixes with tons of high end it is probably not because it is an aesthetic choice, but more likely because they are compensating for the fact that they can no longer hear high frequencies with the same sensitivity as those whose ears are still undamaged so they crank up the high end.
If you stay in this business long enough, you will get permanent hearing damage. How much depends on you and the projects you work on.
If it is any consolation, many of the kids who buy the majority of music these days also have permanent hearing damage because they constantly listen to distorted music at high SPLs through their iPod ear plugs, which probably cause more damage to their ears than your screaming monitors cause to yours. You are probably pretty much in sync in terms of the degradation of your hearing, but eventually you'll both be severely disabled.
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