one good reason to use up currently treasured stationery is that the styles become a bit dated.
oh my gosh, yes, Jean, I know what you mean! I remember taking a look at my first few stationary--the ones I bought at our school store--just before they got damaged and thought to myself: "Oh my god, this is ugly." Like, no mincing words at all! =)) My current obsession right now are quirky characters. The Japanese are into characters. They have stores dedicated to characters like Snoopy, Hello Kitty, Pokemon, etc.! It's not something that I see in my country, and I've always been a cartoon sort of girl (in contrast to tv series like GoT HAHAHA), so I was very very fascinated with Japan's affinity for characters!
Oh my word! I thought I was the only one! I have a full bin of stationary ... I have trouble sending them too. The cat one you shared! Love! 
I have started to get better about actually using them now though. I think for some time it was a guilt that I didn't make it so I shouldn't send it to someone else. But I'm getting over that. 
Omg, do share some photos, Erica! I'm more of a dog person, but the cat one was just too cute! Haha.
Much to my dismay, I've decided to take the plunge and use some--especially the ones with a lot in them. Although lately, I've been obsessed with paper marbling, and make postcards with it. God I love paper haha!