The idea that WSS as an E4 makes any kind of sense whatsoever is ridiculous.
The problem with giving highballs E grades is that lots of people for way too long have conflated doing highballs after lots of work with onsighting trad routes. How many people have actually onsighted WSS?
If you compare doing it after work to headpointing trad routes, which is the only thing that actually makes sense - then WSS would be at least E6.
And Layby would be E5, Careless would be E8 etc.
ie: headpointing Careless is probably a bigger deal than headpointing E7/8's like EOTA or Gaia, probably not as big a deal as headpointing E8/9s like Meshuga.
flashing Careless is pretty much world class - bigger deal than flashing EOTA or Gaia, but probably not as big a deal as flashing Meshuga.
That's the only way it's actually consistent. The downside (at least to people trying to make a living out of hard headpointing) is that means that lots of "E4 climbers" suddenly find they can and have climbed E7's - which makes hard E grades suddenly look a lot less remote.
Easiest way to deal with all that is just not to give highballs E grades. And certainly not to give them completely pointless, inconsistent and confusing E grades.