We have a large Wideline-10 inventory so I'm biased.
The work pretty well for a mid-sized line array. With 16 boxes a side you can have quite a nice rock and roll PA, and depending on your use, the Wide pattern can be an advantage.
We do a bunch of outdoor summer festivals and county fairs, and we do a half a dozen or so arenas where the wide pattern is helpful.
It all depends on what you are doing.
I would also argue (and have in the past) that while for a permanent installation you would not spec a pattern much wider than the room, I have used the Wideline numerous times in narrower rooms without detrimental consequences. These are rooms that I have used several other mid to large sized PA systems and am quite familiar with.
Most of the people who I historically had this discussion with were basing their argument off the theoretical.
They are not useful in every application (ps don't use the for delays, Mac) but the work well for many things.
Jason