At least Wimbledon makes an effort to recognize that grass rankings are different from overall tour rankings. Much better than Roland Garros in that regard. I wouldn't have supported their old arbitrary system, but the current formula seems pretty good. As things stand right now, I think the seeding is fair.
Perhaps the sport needs a two year ranking system or a different method for protecting the ranking of injured players (I'm not necessarily in favor of either of those ideas), but that's not Wimbledon's responsibility.