I wanted the HC2 horse.
Alot.
Whole bunches even.
BUT I found out about the season late and had a string of bad luck (well, not a string, things went sideways at random times, but still).
So, I didn't get it. Didn't really even get close.
Which leads me to a suggestion:
Give people who reach a milestone the option to select a previous season's reward instead of the current one.
This way people can get the rewards they want, even if it was last season's. It's just a cosmetic, it's not going to affect power in any way.