i don't understand the big issue for not being able to mine directly into an exchange, but maybe that a web wallet could solve a bit of it...
I'm positive it's what I wrote earlier:
It's a problem if they allow it because if a
mining pool has a problem, people blame the
exchange when the coin doesn't show up in their account. And mining pools VERY often have problems. Especially CryptoNote pools, for various reasons, not the least of which it's all so new and still more ore less where Bitcoin was about 4 years ago. Except Monero, which is so different from Bytecoin at this point it's almost its own different class of coin.