Why are some of the Legacy skins priced as legendary?

Basically while waiting for the Star Guardian Jinx sale, I started thinking about all the legendary skins I've gotten. Some are just damn well amazing, like Final Boss Veigar and Battlecast Cho'Gath, and others kinda show their age or aren't really up to par with legendaries now a days, really just Brolaf. But then earlier when I got Blackfrost Anivia from crafting I remembered I had to disenchant an Annie legendary, Annie in Wonderland if I recall.

But then that popped up the question: why the hell is that priced as a legendary skin? In fact, why were many other skins like Alien Invader Heim and Firefighter Tristana priced as legendary?!?! Aside from having unique models and appearance, and for some special particle effects, nothing about these skins really makes them seem they should be legendary. They don't get a different voice over, they don't get completely new unique animations, all they ever really get, at least from what I can tell, is they get a new appearance and sometimes new particle effects. Why are they priced as legendary when they could easily drop down to 1350 or even 975 for some? (And don't say because they're legacy. Zombie Brand is also a Legacy legendary but actually feels like a real legendary.)