Now, Dungeons and Dragons (in the olden days) was based around Attributes and their influence over variables, represented by rolling dice (usually a twenty sided one). So, let's say you went to hit a Goblin. You rolled a Twenty sided dice, added your Strength's To Hit Bonus, and compare it to the Goblin's AC. Well, it was more complicated than that (they used a lot of tables and charts) but essentially the system was used in order to represent what your character could do and how this influenced situations with variables factors.
Morrowind used this system. Everything you did was based on a random roll that factored in your Attributes and Skills. However, because of the addition of Skills, atrributes took a back seat. Rather than directly effecting the variable, they indirectly effected it by effecting skills.
In Oblivion they became even further seperated from the variable. Combat was no longer based on variables, but rather on a more realistic combat system. It seemed, to me, that Bethesda was trying to move away from statistical variable systems and more into simulationist design. You don't roll to hop over a ravine, you hop over it and fail or not. You don't roll to hit a monster, you simply hit it and the damage is effected by your skill.
Personally it seems to me that attributes have become vestigial organ of TES, and Todd seems to think so as well. Skills do what attributes used to do, and having 'main stats' is no longer necessary because there are fewer and fewer OOC (out of character) variable mechanics to deal with. Essentially, the games are more Role than Roll Playing.
That's what it seems to me anyway.