Does it? (I don't know of anyone suing NICE, but they've certainly brought lawsuits against GP practices and hospital trusts, and won substantial damages for malpractice and/or judgements requiring the provision of treatment that was at first denied on various grounds.)
Meanwhile, the NHS bodies that deliver healthcare -- be they PCTs or fundholding GP practices -- don't have a profit incentive for excluding people with pre-existing medical conditions from receiving treatment. (They may have a cost control incentive to for denying anomalously expensive treatments, but that kicks in at the opposite end of the supply-and-demand chain: and it's defended by reference to metrics like quality-adjusted life-years per unit expenditure rather than the requirement to show a profit.)
Finally, the "loser pays" rule has been greatly undermined by the widespread adoption of conditional-fee lawsuits for civil damages in the UK over the past decade.
Well, I suppose so, the UK's NICE (http://en.wikipedia.org/wiki/National_Institute_for_Health_a...), much like our CMS (http://en.wikipedia.org/wiki/Centers_for_Medicare_and_Medica...), establishes the impersonal guidelines, but in the US only those over 64 or on Medicaid are impersonally bound by them. In practice when our "parasitic insurance industry" addresses this it's about providing coverage beyond the CMS guidelines, since the latter are a floor which our legal system won't let the "parasitic insurance industry" go below.
That legal system and most especially its lack of the English "loser pays" Rule is probably a greater influence on costs, especially since the NHS has got to have some level of sovereign immunity.