First off, really enforcing it would be a start. In addition, only a handful of companies have ever been banned from receiving government contracts for failure to comply with the laws. Until we get serious and treat discrimination like the crime it is, affirmative action will remain somewhat hollow. There are other things we can do to improve, or supplement, affirmative action. To the extent the Congress took us back to a more stringent standard, fine.
Similar evidence exists for graduate level tests.
I've heard people argue that fighting for governmental protections like affirmative action serves primarily to legitimize the government's authority and takes energy and focus away from fighting for fundamental social change. Well, I agree, if the persons fighting for such minimalist protections end their analysis there, without linking the fight for affirmative action to the fight for broader social change. To the extent many proponents of affirmative action fail to make those connections, they're not real allies. However, to the extent we make the connections between the need for affirmative action, and full employment, and education as a right rather than a commodity, and workplace democracy, and ending poverty, then I think the fight for affirmative action can be empowering, and actually help demonstrate the overall sickness of the system. They don't have the time.