This may not be very specific to Yaffs but a generic question on Log structured flash file systems.

Log structured file systems are designed to avoid seek latencies (In case of hard disks) and to handle wear-leveling in a way (in case of flash disks).
If a flash device is handling Wear-leveling & Bad block management, what is the significance of a log structured flash file system?
A non-log structured file system should be as reliable and as efficient as a log structure file system.

Thx,
Venkat