Things like transmog, toy, maybe pets and mounts too should be account-wide.
I spent quite the time collecting all the stuff back in the day (especially after the wardrobe-sytem), I have fond memories of it, but I don’t have the time (and the patience) to do it again on classic. I can’t see any wrong making it account-wide, people won’t play more or less the game because of it.
I have very good news for you…
I am all ears 
Honestly I don’t understand what is going on.
In retail almost all what you mentioned is account wide. If not all …
Or you want to have all your retail collection available in Cataclysm / Classic Era Realms?
Indeed, yes.
Oh so you want the Retail feature, Account-Wide being exported to Cata+Classic.
You see, this is GD and people were confused for a second why you’d suggest something we already had.
Honestly, don’t know how to react properly.
I’m mostly playing retail version. I have collected many things over the years.
If I decided to go for different version of game I would not expect the collection to be transfered. I mean, you’re playing the different game version for some reason, right? Or?
I gave a shot to Classic so I can experience many aspects of gaming from the past. That means - also collecting stuff like toys, mounts etc.
I know some people would disagree, but honestly what is your point going to play different version of game, and not be willing to farm stuff which is rewarded in that game version?