We do need altcoins because for the main reason that we did miss bitcoin at its low price. Most people wanted to buy an asset as a whole. Not just by .001 something or so. Altcoins are making investments greater. You'll be lucky enough if you start your investment with below 1 USD token, and that token became 1 USD or 2. That is a win. So we need altcoins.
I agree with you on the things you write. And because of the high price of Bitcoin it is very costly to send money to any one. That's why people prefer other subcodes to send money.
It's not just that, altcoins are driving the innovation, bitcoin has done that but now it wouldn't as much as altcoins do