Trading volume is very small, there is no point in new exchanges.
That's not how it works. New exchanges bring more exposure to the project to new investors which results to larger trading volumes.
Exactly.
Bigger, well-known exchanges bring more liquidity and trading volume.
Some people in the crypto world refuse to touch smaller exchanges, and only trade on Binance, Poloniex, Bittrex etc. (I personally like finding gems before they hit the big exchanges)