Why are you making a lot of pair to the USDT, it seems no good in my opinion, it will be better for you put ethereum pair. It will be encourage a lot of users. But i don't know why must USDT.
because in 99% of the times 1 USDT is equal to 1 USD which means those who don't want to go through the verification process or endure the high fiat deposit/withdrawals fees can easily trade with USDT or tether and the transactions of it are also fast, much faster than fiats are! so you can easily deposit and withdraw fast and trade whenever bitcoin (or other altcoin) prices are moving and don't miss out.
but eth price is too volatile and there aren't that much interest in these types of markets even in bigger exchanges.
although I personally like having this option, specially with LTC market (meaning altcoins/LTC)