Not a big issue at all for me, but yea, I do think Riddler has tended to be less big. Even IGN addressed the point:
http://www.ign.com/articles/2017/06/...an-25-review-2The only sticking point is the fact that Janin's beefcake approach to rendering male characters seems a little out of place when it comes to Riddler. Rather than a thin, wiry shut-in, Nygma looks primed to hit the beach and bounce around a volleyball with Dick Grayson.
I'm fine with some added fighting prowess, but I don't think you need to overmusclularize Riddler to have that.
Sale's alternate cover had Riddler taller than Joker, which was really weird to me because Joker has like always been shown to be particularly tall, since the Golden Age. Taller than Batman some have shown/believe.