Talks of 'stimulating small business,' etc., I think, are often popular because they fit _ideologically_ into the neoliberal agenda of tax cuts, relaxation of regulations, union-busting through subcontracting, etc., though activist proponents of such talks are unlikely to be aware of this fit. (_In reality_, however, small businesses can't possibly survive without heavy-duty regulations of large firms.)
Many left-liberal activists are unfortunately 'reverse size queens'; they love the idea of 'small is beautiful,' though there is no reason to think that small is necessarily more democratic, ecologically sensible, etc.
Also, there is a question of what the term 'small business' means exactly. The term's populist connotations may be used to mask quite sizable and profitable business activities that should not be treated any differently than other firms.
Yoshie