Um, yes, it very much is cheating. Thats like saying speeding isn't against the law because anyone can do it. Just because some people get away with it, or because the authorities don't bother to do much about the issue, doesn't somehow make it legal.
Or to use another sports comparison: just because many other cyclists were doping as well (though not nearly as successfully), doesn't mean that Lance Armstrong wasn't cheating. Without the cheating, he never would have won anything.
It's not surprising that teams make use of it if they see that no one challenges them about it. It's still cheating though. Just like it was cheating when the players hooked, held and interfered to their hearts content back in the DPE. They knew they would get away with it, because the league didn't care about it, but it was still in breach of the rules.
Sadly, you are correct in that teams don't want to fix it. It does seem like teams follow the approach of the average Joe who thinks he will be the one who happens to become rich someday and is therefore against taxing the rich people properly, and thus don't care to fix this blatant loophole as they might get to use it themselves one day.