Because as a character he was naive as hell and brought about the resurrection of Onaga. Plus he is just an old man version of Chameleon. He's just really unoriginal

Well aside from TRULY unpopular characters like HSU HAO, MOKAP, DRAHMIN, and SHUJINKO it really seems like most of the other newer characters just fall somewhere inbetween popular and unpopular.
I actually really enjoyed a lot of the newer characters...eventually.
I liked ASHRAH, KENSHI, LI MEI, FUJIN, REIKO, NITARA, FROST, and TANYA from the very beginning.
Mostly i dont pay attention to the so-called unpopular business tho and i really liked playing as Mokap (especially since he got those cool telekinetic moves in Armageddon) and i loved Hsu Hao's weapons and fatality. They were both just a bore as characters...

I liked kira actually. I pretty much agree with moseph's list though from what I've seen of other people.

Most new characters from MKDA -MKA with some exceptions are unpopular.

In my ten years of MKO, I can safely say that this is the best sig that any active member is currently rocking. If it wasn't for my failing memory, I'd be tempted to call it the best of all time.