According to a Namco Bandai Partners representative, Microsoft did not pay for any exclusivity surrounding Tales of Vesperia. That isn’t what held up a North American/European release.
It'd be a shame if that was the case. Having Project Vesperia move onto other projects is certainly the most plausible reason for the refusal to localize. I think people tend to forget that most localizations require the original team's help in creating the localization and without them its a no go. Hence why that Grand Knights History localization got cancelled.
AnimeShinbun is a community of awesome people posting and discussing the latest anime news. It’s part of NewsBoiler, a network of social news sites covering today’s pop culture.