By this logic, Canada, Brazil and Australia are also Empires, since the territory of their countries consists of land annexed from indigenous peoples.

I'd see no reason not to call them empires as well. The word empire doesn't in itself imply tyranny or genocide etc, any more than it implies benignity - the word just means a set up where a central government holds together an assembly of disparate states. For example, the United States.

I still find it strange that Americans seem so sensitive about this kind of stuff. It's like those stories about elephants being frightened by mice. A standing invitation to any mouse who's feeling a bit low to say "I know, I'll go out and frighten an elephant, that always cheers me up." (And please note I'm not recommending that any mice do that - it's both dangerous and unkind.)

Drop the Star Spangled Banner because it's too difficult to sing, in favour of America the Beautiful? I'd call that dumbing down. Better to learn to sing it properly. I suppose the French could drop the Marseilleise and sing Frere Jacques instead. But they won't. (If you can't hit the high notes in a song, simple enough, just sing them low instead.)