The problem is that as people age they do tend to shift their opinions to the right. Obviously not everybody does but it is a known trait.
I saw some research (which was conducted on USAnians, so may not apply to the same extent in civilised countries) that suggested this effect was simply an artefact of wealthy people living long enough to become old.
The moral panic around trans people, on the other hand, is something that's being deliberately stoked for political aims. That's why it wasn't a 'debate', let alone a mainstream issue until 2016. The people directly involved were quietly getting on with establishing legal rights, providing medical care and regulating sport until [left as an exercise for the reader] decided it would be a useful element in a culture war.
And the thing about culture wars is that they provide an easy way to get your name in the papers with "$celebrity expresses opinion". And since the existence of trans people is now being framed as an attack on women's rights, that means every female celebrity is now entitled to an opinion, no matter how ill-informed.
