I agree it would be a difficult decision for parents of 12-15 yo, and in some ways I'm therefore pleased it's been taken out of their hands (for now at least). I don't doubt that the vaccine is "safe" - as far as we know now, and there would be some benefits (in terms of reducing their/ others anxiety to be around them, and reduce the risk of disrupted schooling at least). But it doesn't seem to be as "safe" as other childhood vaccines to the individual child, and also the benefit isn't as great in reducing the impact of potential serious illness to the child. If it was left to the parents, that's a really hard decision to make against expert advice. And if there were a political push to promote vaccination in that age, it would make things even more tricky.
Personally, I acknowledge I'm no expert and am willing to defer to those that are in these kind of things. So if the JCVI/ NHS/ gov say "we think you should have this", I generally say "OK, go on then...", and I don't go round looking for reasons I shouldn't. That may be very careless and blasé, but I tend to think I wouldn't know who else to trust... If I go to Google I'd tend to focus on "official" websites anyway, and while I may look at alternative views, so many of them are bonkers and I trust any obvious issues would have been addressed by the trials/ data reviews etc anyway. But in this case, we have the experts saying "on balance, we don't think this is a good idea for otherwise healthy children" - and potentially the governments (and therefore NHS) overruling this and saying "despite what they've said, we think it is a Good Idea" and presumably pushing the vaccine programme through the usual channels. It just seems a way of undermining expert decision and creating doubt among the population! (oh well, the experts didn't come up with the decision we wanted, so we're going to convene a committee of different experts and ask them again...). I realise they are making the decision with different weights on different risks/benefits - but it just doesn't sit well to me.
Happily, DS is under 12 so it's not something we have to think about for a while...