Why do they keep everything the same? All those fees are going to the miners anyway, not the exchange.
Segwit is only ~2x savings in fees. I'm guessing the exchanges aren't taking that much heat re: fees from customers. Most of the exchanges are busy adding more shitcoins, rather than implementing Segwit.
It's fine, anyway. Segwit was opt-in for a reason.....
But they should take the heat regarding the fees. Its the same with localbitcoins.com, they should looking for other solutions instead of going for the easy way like increasing the fees.
Having said that, Bitstamp is one of the best examples that exchanges should follow.