I don't think they need to do that. These are meant to be a time limited exclusive thing, tied in with the launch of Moria on the legendary server. They are meant to be unique and they are meant to pay for their own development time and resources by being a purchase only item. Nothing at all wrong with any of that.
But even the notion that buying one of these bundles would screw up the collections of alts is just mind boggling. People will want to buy these things, because of what they are and represent. I've no idea why SSG would limit the items inside to one per account. I get it with the housing items - they don't want players placing spares into the houses of other players that didn't part with the money, and that's fair enough. But there is no reason why they should restrict the pet and emote to one character only. If they are account bound, they can't be given away to those that didn't buy, so there is nothing to protect. In fact, if players have lots of alts running around with this pet and emote, it's likely more players will see them and try to find out where to get them. If I were to buy this bundle (which I definitely won't if this stays as is), I'd now open it on my main on EN, because she is my main collector. However, I don't play on EN now, so no other players would see the pet or emote. How's that for word of mouth advertising. However if they were not restricted to one character, people would see them on 9 alts on the LS - that's good advertising.
I'm sure some folk in marketing think, Oh do it this way, if x doesn't buy it, then x doesn't get that goat.
What they don't think about is, if x doesn't get that goat, their collection is moot, and all other goats, alongside all horses, become a lot less relevant in the process. If they miss one, then they may as well miss twenty as the result is the same, an incomplete collection.