Justifaction: Defense is a special interest. It's mostly concentrated in sunbelty areas as part of a patronage system. Why should rustbelt voters subsidise the economy of affluent areas?
I get your point, which is that spending on urban regeneration will be good for the economy of the entire country, just as spending on defense is good for the entire country. On this I largely agree, provided that the spending on urban regeneration truly will improve the economy of the areas in question by stimulating growth in lasting industries.