The thing is Gruber is the exception not the rule. Far more action movies have been made with one note villains just there to challenge a compelling hero than villains that are compelling on there own. Stories have always been the heroes journey with the villain as obstacle on that journey. Some actors make better use of limited time onscreen than others and come away with a compelling character anyway, like Anthony Hopkins in Silence of the lambs. Some can't grab your attention that way to make themselves memorable or compelling. It's not just what you're given it's what you do with it.
While I agree it's difficult I don't think it's impossible and I'd prefer they shoot for impossible rather than going with doable and safe. Especially since Scott and the cast acknowledged the villain issue and said this guy solves it