FOMO is mostly fine, most players understand that “seasonal” mounts and titles mean exactly what they say - “seasonal” or " season X"
I think the issue comes when they recycle certain old content and make it harder than the original version for worse rewards (cough Mage Tower cough)
It’s like, if you’re going to make it harder than the original, if you’re going to make us slog thru 200-300+ wipes and spend hundreds of thousands of gold on it… just let us earn the friggin original rewards 