Yes we need altcoins but we do not need more then we already have i think we have like 1200 coins in total and nobody follows them all everyone follows the most popular ones and they only try to follow one if they see how much they can make.
Yes we absolutely need altcoin because we cant use and have bitcoin without altcoin cryto currency . Altcoin is so very helpful in bitcoin. It is also most known and been tried to almost everyone of us .