So after starting a thread looking at the merits of x11 over existing algos and not getting even 1 ....yes not even 1 clearly verified advantage the thread seemed to become infested with dark coin destroyers.
Still going on about this? I'll give you one reason, which is what the dev has explicitly stated. The new algo was created to allow a decentralized distribution in the same manner as bitcoin, i.e cpu miners first, followed by GPU, and then eventually ASIC. If the dev had just used SHA256 from the start, only ASIC miners would be able to mine the coin. A new algo was required.