reimero,
I wouldn't worry too much about a "universal" system key aspects of role-playing. The universal system concept is not a new one, and generally what happens is that a company tends to use one game engine for several RPGs. In fact, out of the list og games you current play, all of them were systems designed as part of a company's universal rules system. AD&D was reused in early TSR RPGs like the orignal Boot Hill and Meptamorphis Alpah/Gamma World; Twilight 2K was used again in Traveller: New Era; The basic system used in Cyperpunk was also used in Mekton; The system in L5R, with some changes was reused for 7th Sea; The d6 system from West End's Star Wars RPG was resued in moderately altered form for the DC Heroes RPG, Hecules & Xena RPG and others; the Icon system was reused, although for only a limited release for LUG's Dune RPG; and The Basic Role-pLAying System used for CoC was used by Chaosium for most of thier RPGs, including RuneQuest, Ringworld, ElfQuest, and the Strombringer/Elric line (BRP in many was was the first universal RPG system). The rules for the Bond RPG were reusued in a couple of Victory Game's board games, including the James Bond Assaut Game, and a WWII board game.
The D20 concept isn't necessarily a bad one- it allows many companies to profit off of the D&D cash cow, and even introduce thier products to a new market. The only problems I can see are if companies drop thier other products to exclusively support thier D20 line. So far, that hasn't happened. Comapnies liek AEG and Chaosium are still supporting thier own systems in addtion to D20.