I usually avoid
Vryn Wingmare and friends in my decks, even if I'm heavily creature-based - I prefer cards that are more synergistic with my gameplan. That said, I suspect they're better than I think they are. Generally, I think that ramping is one of the strongest things to do in the format, and setting your opponents back in mana by a turn should, in theory, be equal to ramping yourself ahead by a mana. Is Vryn Wingmare actually
Wood Elves in disguise? Maybe.
..of course, the flaw in that logic is that I don't think EDH decks are quite as polarized in their contents as decks in other formats. Looking at Legacy, a deck like Delver runs ~12 creatures and 28 spells, with some decks like Ad Nauseam or Storm potentially playing zero creatures, which means Death & Taxes with its
Aether Vial + creatures strategy is getting a large relative bonus. In contrast, I don't think many decks in EDH are going to scoop outright to this sort of effect, nor are as many decks running the 40+ creatures to ignore them outright. Plus, there's the issue of games going longer - if people routinely get to 8+ mana, then denying a single mana matters less than games where people end on 2-4 mana. (The math does change a bit if you expect people to be casting multiple noncreature spells per turn)
Anyway, I don't think these are staple cards, but I should probably be playing them more than I should. They do tend to fare pretty poorly diplomatically though.