I found it pretty surprising Bale dropped out after spending a couple of years trumpeting the tournament and prepared to run the wrath of the Welsh. I can also see that Pearce, Giggs etc would be pretty pissed off but it is entirely possible to be too injured to front up for a major tourney but ok for some measured on field time in casual pre season football.
Well Giggs shouldn't be pissed. How many times did Giggs suddenly have an injury according to old whisky face, dropping out of a Wales squad only to play for United a few days later? Pretty much every time a Wales game interferred or was close to a United game. He only has 64 caps in 16 years before he "retired" from international duty in 2007. That's 4 matches a year on average. Robbie Keane has 120 games in 14 years for comparison.
That said, I'm not surprised Bale dropped out at all and I very much doubt he had an injury too. We have a new manager, and we can't afford our most important player to be away for our entire pre-season preparation and risk him getting injured playing for someone else either.