When was the last time you summoned a mount that wasnt one of your top 10s?
How many pets do you have that have never been summoned or used in pet battles?
Would you even notice if 90% of your transmog collection disappeared?
What compels us, as gamers, or just humans in general, to collect everything we can, even if we have no intention of getting ANY use out of it?
When I went to transmog a character I would notice pages of options missing.
I only collect things I want. I have no need of complete sets if only one piece is to my liking. If I don’t like a mount I don’t bother getting it.
It be a feelin of progression dat isn’t gear for me. At first when I be startin ta play it was achievement points! Dey can’t even be for anything just a number lol. Pets, mounts, toys, transmogs be giving the same feeling of happiness just to have it.
I love ta see something new added to my collection!
im a collector, be it mounts, pets (kid of) and transmogs. dosnt matter if i dont use it, its the hunt for it thats the fun parts
So we can show them off to people who don’t have them ( in both positive and negative ways), and tell stories about how we got them.
Because it feels good to collect things?
This isn’t some abnormal thing - people have had non-utilitarian collections for as long as people could do things other than struggle not to starve.
obsessive compulsion brought on by PTSD from childhood trauma caused by neglect. The people you are trying to impress with your collection will never be proud of you. And so you keep collecting, as time marches on.
I add all the mounts I like or want to see on my favorites and just use the random favorite mount button.
As for transmog its nice to have options. Its just hard to match color palletes.
If only wow had Destiny 1 Shaders.
They locked 4 out of the 6-7 dragonhawk mounts behind mount collecting so it’s really the main thing that compels me, slightly (realistically I’ll just remember to be subbed the next time BC week happens for once and grab the eclipsion hawk)
Because I am too poor to collect stamps/coins.
Well not poor. I see extra money accrue after a few months it goes to kids college fund and such.
that can explain my situation. was a Navy brat growing up, and had to toss many things before i was ready to let them go, when we had PCS moves every three years. sucked throwing out comic books and Cracked/Mad magazines
You would notice all of that especially if you were a mount collector for the achievements.
I have over 1000 battle pets, some I’ll never use, but you never know when there will be a pet battle that will win with a specific one that I have.
I collect transmog because I match it with my mounts, pets, and hair coloring.
It’s fun.
I used to buy tcg trading cards and I would win a mount very often. Now several of the mounts and pets I have are worth over 1000 real life gold.
I’m glad I have everything I have worked hard to get. It’s a fun challange and I’ll continue doing it.
If 90% of my Transmog disappeared, I would’nt be playing the game.
Thats an… interesting take on simple collecting
Nothing.
Which is why I don’t do that.
Vanity Collections are pointless. Transmog is the closest to being meaningful but even then, as you said, most people have handful of sets they pull from but have pages and pages of options they’d never miss.
(though it’s probably more like a handful of sets per character, or at least armor type)
This is a question that goes beyond World of Warcraft and I’m no psychologist so I can’t say 
All I can say is that I enjoy completely finishing something and collecting gives me that.
Many things are collected incidentally while playing for other reasons, or trying to collect other things. Many other things are used for a period of time after attaining them before falling into disuse, or perhaps infrequent use, but they are used until we’re on to the next thing.
For me it’s the overwhelming feeling of accomplishment and reward i feel when Blizzard adds a mount collecting achievement for a total that i hit years earlier 
I just like to horde stuff.
My brother and I are playing Pokemon Arceus. He’s far more along in terms of progress since he sinks more time into it and my focus is split between several other games.
Comparing our inventories he has somewhere in the realm of 30-40 potions in total. I have 70 potions in 3 different stacks. So while I play much slower by constantly gathering resources I’m loaded up for long hikes in the Pokemon wilds.
Guess it just boils down to your own playstyle.
I’m with this guy. It’s just fun to collect things.
And yes, I do use a lot of my stuff because you see RNG in this game is crap and when you are camping, again, a world boss and some dorky alliance player is sitting on their fancy mount you just have to one up them and get on a better mount, that’s when you actually use more than 3 mounts, when you want to show alliance whose boss.
No idea, I usually only go for things I like and never collect things I’ll never use. I don’t have tons of mounts or pets compared to most for this reason.