Bitcoins without altcoins wont be as interesting as they are right now, We wont have anything to exchange for BTC and make profit, in fact many people make good profits with altcoins trading.
I must say that's not all altcoin helps, though. Sometimes some scamming altcoin would unfortunatelly hurts people's trust on cryptocurrency or btc. Though its uncommon, there is a chance that someone is trying to gain more btc from trading altcoin for the first time and unfortunatelly s/he choose a relatively new coin which turned into scam. When everything's gone, I doubt it'll give positive feedback to the scammed user.
