I believe the major consideration n the first post is minimum good tow speed for the standard C-182 vs. the safe tow speed for various SGS gliders the n poor conditions.
The 182 already wants to fly faster, add in margins for poor conditions (gusts, etc.) and you are getting really high in what is safe for lower speed gliders.

So....do they add VG's to lower the speeds for the towplane to open the safe window for some gliders, especially in poor conditions?

That is my interpretation of the original post...

;-)