People are unreasonably attached to the heroism buff simply because it was quite strong. If it was a move you just cast on yourself that gave you heroism and only you I would probably agree, however this is a group buff and it was silly to ever limit it to a single class in the first place. Do you enjoy the feeling that you are being brought purely because you provide a thirty second long buff? I certainly wouldn't.
People say that heroism was a defining shaman ability, however when I think of shamans I think of totems, shocks, chain lightning and harnessing the power of the elements, things that the class is actually based around that you use all the time rather than a buff that you use once every ten minutes.
OF COURSE your defining abilites are going to be ones that you have to use. Would you play a frost mage and expect not to cast frostbolt? I don't see how Oneleg can say "No! This ability doesn't define my class because you are supposed to use it!", that just doesn't make any sense to me.
Besides it's not like you're the only people this happens to. Paladins used to be the only people to provide Blessing of Kings. This too is a powerful buff, why is nobody whining that druids now have it too? Because it was really inconvenient.
Just like it was really inconvenient for small, shaman-less guilds that they didn't get heroism.
There really is no reason for anyone to be upset about more than one class having heroism.
Blizzard have even said that they are no longer balancing around the "5% less than pure DPS classes" idea, so that shouldn't be a problem to you.
Shamans are still raiding, just like they always have. Nobody is dropping shamans from their group list now that they no longer bring a buff.