I may be in the minority here, but I don't have a problem with skaters withdrawing from the Grand Prix Final, if they think it's not in their interest for health-logistical-strategic-or other reasons. I have always thought it was an overly-contrived, semi-bogus competition and not worthy of being taken in the same serious vein as country Nationals, Euros, FCC, Worlds, Olympics. Even the component GP events are arguably more important than the Final, as those are the best early season opportunity for top skaters to present new programs in front of judges and audiences...and make adjustments as necessary. Of all the competitions, the Final is probably the most easily "sacrificed" even though there is prize money involved (not that much though except for top 1-2 finishers). The formalization of and adding a Final to the original GP series was pretty much an ISU concoction to benefit itself rather than the skaters.
It doesn't help the non-Asian and especially the North American skaters, that once again the GPF is in East Asia (5th time in 10 years and 2nd year in a row). Adding up travel, recovery, pre-competition, competition, return, recovery, and you pretty much blow about 10 days of your life where you lose productive training time. Not to mention having to deal with long-haul transpacific 11-12+ hour flights and the risk of picking up illness during the travel, in a very bad flu season year. If Tanith and her dentist felt now is the time to tend to her tooth, so be it. If there was an ulterior motive such as wimping out in the face of D/W and V/M, so be that too. They'll all meet up soon enough.
(PS to above: Michelle DID skate the GP series for many years and then decided enough was enough around 2002, except for stepping in at SA on some occasions as a fill-in. ISU didn't like it but by that point, MK could pretty much pick her involvement in competitions.)