Very good question, here is the answer from the team:

Bitsupra idea was made at second quarter 2015 and Ethereum platform was at early stage at that point, that is why we used Counter Party and our name has "Bit" word inside it, but the advice telling us Ethereum is more suitable to run this kind of platform can be half true that is why we want to state this: we always pursue the improving and high quality development of Bitsupra, that is why if there is the need of switching to Ethereum platform because of crucial development environment, Ethereum currency going mainstream, Bitcoin having major technical problems, XCP platform having major disinteres or technical problems, among others; we will switch to Ethereum.