Is there really need to build Block Device Emulation over UBI?

[Nancy]

Hi,
   Is there really need to build Block Device Emulation over UBI? Why
can't use the mtd_blkdev.c and mtdblock.c directly?
   Thanks to gluebi, make UBI and MTD become one. More interesting
thing is,  volume can be treat like a mtd partition. mtdblock.c do not
have wear-leveling and bad block management mechanism but UBI has.
gluebi make all those functions mix together right?
   I have tried, and it work.