The main question is: Do we really need altcoins?
First of all, it was quite difficult to read your.. text. You should learn to format it, really.
Now, altcoins are not useless. They are at least a wonderful training ground for new ideas. Some of those ideas are incorporated into Bitcoin, some of those coins become used by themselves.
Maybe you know that Ethereum or Monero were not the first altcoins. Monero was not even the first cryptonote coin!
Also you are wrong about only BTC-ETH-XMR being accepted. There are other altcoins accepted here and there. Not so many, I know, still, more than nothing. So we have to give them a chance (of course, I talk here about the legit new coins, not about the useless forks or clones).
There are altcoins created to serve within their ecosystem and be their payment system. The ecommerce industry alone is a trillion-dollar industry. So there are sufficient rooms for every project to explore this area. But the truth is, very few projects are genuine to the core. In short, we still need altcoins just make sure that you are dealing the authentic ones.