Segwit is a soft fork. Soft forks are not good since it introduces complexity. Bitcoin Cash will be better off in implementing some changes of segwit via hard fork. We want hard fork because it is simpler than a soft fork. In a soft fork, you will have to mind about people who don't upgrade, whereas in a hard fork, all will follow the new rules anyway, so the code can be made simpler, which is what we all want.

I also said some changes. Segwit is not a change by consensus, a supermajority is not consulted before the change, that's why it is a soft fork, because some may not want it (which we already see now in BTC). The BCH community doesn't want a change included in segwit: weight calculation. It is against the idea of a free market, so it is excluded from BCH code.

There, I have answered my own question, from the good answers here. Improvements are welcome :)