Personally, I'd find it more than a bit creepy if some Ironforge Exchange writ guy decided to move into my bedroom and offer me 'work orders' and say he can use my 'services' whenever I asked him what he was doing there.
This just doesn't make sense to me from a realism point of view (nor from the creepiness factor perspective) and it's not something I expect to change at this point. It just makes sense that if you want to go do work for someone, you go talk to them and get your order.
Fuel vendors was something people had asked Frizznik long ago, and while he said at the time he didn't see a reason why not, as it turns out there IS a reason - housing is an instance, and is currently not coded to support what would essentially be NPCs staying in your home when the instance disappears. I've already made a few enquiries about how much pain would be involved to change that, however, our brilliant engineering team are the ones who will answer that. IF it turns out to be possible, I can assure you that you'll hear about it, since I'd really like this convenience too.
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