The ONLY reason that I still used WoL for the majority of this tier was their expression editor. The real power of logs was never simple DPS reports (you can get those through in-game addons) - but being able to view raw logs and reconstruct what happened during a fight.
Until yesterday, I didn't notice they had updated it (haven't had to check much since progression is well over), but from just playing around with it, WCL's new(ish) pins system is actually enormously more powerful once you get used to the syntax.
There's really no reason to use WoL anymore, but people are just used to it since the name is synonymous with "logs" right now. I suspect it'll go the way of WWS when 6.0 hits and everything breaks.