Starlin has gone on record as saying he thoroughly enjoyed Aaron's Thanos. Plus, anyone who's read Thanos for years (and most especially have read the 2003 Thanos limited series issues that Starlin did as well as the Infinity gauntlet lead-in issues of Silver Surfer where Mentor described Thanos' childhood) know that Aaron actually got the origin pretty much spot-on. The only ret-con was the fact that Thanos fathered progeny, which was very likely an editorial mandate (re: Thane and the Inhuman tie-in) and cannot be blamed on Aaron.