No, the reason no one touches it is because the courts decided it over 100 years ago. The first major case was Lynch in 1844, and the last was WKA in 1898. Since then, there has been no doubt about those born in the US of alien parents.
Cruz is actually in a grey area. The courts have never tried to decide if someone born overseas to US parents was a NBC. Traditionally, they have been considered NBCs, but there has never been a need for a formal ruling.
Rogers v. Bellei, 401 U.S. 815 (1971) arguably creates a third case of citizenship, for those born US citizens by being born abroad to US citizens - as was Cruz. (http://supreme.justia.com/cases/federal/us/401/815/case.html)
My guess is that if it came to court, the courts would reject Rogers v Bellei and argue Cruz was qualified as a NBC...but I will grant it is an area in dispute.
Or, they might not reject Rogers v. Bellei (as I understand the case) and say simply that "natural born citizen" means "citizen at or by birth," but that in accordance with past common law precedent, Congress has the authority to define who are citizens at or by birth in the instance of those born outside of US soil, and to place residency conditions that could strip some such persons of their (natural born) citizenship.