Well, this is an idea I had while playing my lute
Now that with the newly implemented ECL mechanics can be considered be that all races are almost on par on power with the others, what about being more loose with those races that were more powerful but had some sort of aligment restriction?
It is true that aasimar, tiefling, drow and others for the most part fall in a side of the aligment scope, but it isn't totally unheard of less good/evil characters of those said races while those same races of the opposite alignment spectrum are actually that rare.
What I would propose is being able to play a neutral member of those races albeit with a higher kismet cost, example let's say create an aasimar/tiefling which have a cost of 700 kismet, but that choice would limit in your aligment choices to good/evil, but in the same screen where you can choose those races you would have an extra option that would be "neutral aasimar" and "neutral tiefling" (for example), upon chosing one of those races when you are to select his alignment you would have opened also the neutral aligments.