The UK is suffering from a housing shortage in certain areas of the country and has very few options to expand housing stock that do not involve developing greenfield sites.
I do wish they could have come up with a way to incorporate the existing structures into the new development but this would be perceived as a massive long term maintenance issue and probably not an optimum housing density.
From a city point of view, 2000+ new homes vs three defunct gas holders is a no brainer in revenue generation (£4,000,000 per year in taxes). http://www.bathwesternriverside.com/overview/