Let us not be so dismissive over Jonathan Frakes' many accomplishements within the STAR TREK franchise. First and foremost, he's a solid performer. Second, he's directed quite a bit of STAR TREK, including the biggest Box Office Hit, up until that time: FIRST CONTACT. Without a doubt, one of this franchises best movies. So far, so good. And lastly, ENTERPRISE was not his first guest appearance on another series other than The Next Generation. These episodes on DS9 & VOY saw their ratings go Sky High - thanks, specifically, to Frakes' participation! In fact, it could be argued that, because of this "precedent," Frakes was actually overdue for an appearance on an episode of your precious ENTERPRISE.An "anything goes" attitude is hardly the reason we got TaTV featuring the overweight "Imzadi" twins. As part of their quest for high ratings for the episode and disregard for Ent fans and cast, the Beebs chose TNG characters ...
The Voyager appearance was a well hyped episode for two reasons: John de Lancie and assisted suicide. Indeed, he and Mulgrew were both on the cover of TV Guide. Frakes' appearance may not have been part of the promotion, but it certainly was a minor part, if any.