So it, again, comes down to whether or not it's worth seizing the house. Miles considers that it is not.
They have adopted a general attitude of trusting Bar, and Bar says that it is, although by no means guaranteed, at least possible to get a second door. That possibility is a factor in Miles's decision. Even if none of the people currently in the bar ever gets another door, Miles is going to tell Simon about all of this, and Simon is going to keep an eye out for more instances generally. Miles therefore considers that there is an inestimable but non-negligible chance of somebody finding another door someday - perhaps in a more convenient place, perhaps in a less convenient one, but somewhere.Also, the 'getting a door again' thing seems like a weird thing for them to be thinking about. Whatever your intentions as a writer regarding future availability of doors, given that none of them were aware of the existence of other universes at all before the incident, it'd be a more natural response to treat it as a once-in-a-lifetime event rather than something that can be expected to predictably reoccur under more convenient circumstances.