Yes LBA is rubbish for all those reasons but it does sit next to a very big conurbation. With hard work it could grow to a 5/6 million pax airport and so I don't think it will ever become a housing estate.
Doncaster is completely in the wrong position. People from Sheffield can get to EMA very easily and people from West Yorks will always prefer to use the airport on the doorstep. That is why finningley will never be able to pull enough pax. This is why it simply cannot maintain business routes. Take away the very cheap holiday flights and say EMA or LBA arranges a deal with wizz for example that undercuts Doncaster and then what would happen? Too many airports in too small an area all going after the same passengers. It just cannot work in the medium / long term.