I say this mainly beacuse the thing that most scares my new players is the score/modifier relation, or they brake their heads trying to get it, or they just ignore it and just say what the most experiencied players tell them to do with it, so thinking about that, wouldn't be simpler if this relation just vanished? In the character creation using the choices to determine scores [which is a great idea], the abilities increase 2 by 2, always gives a +1 to a choice made, if you stop to think about it, this conversion is already made: Instead of everything starting on 10 and increasing 2 by 2, everything start with +0 and increasing +1 to +1. About rolling abilities, you could think a new way to do it or just vanishe with it and there it is, no more obsolete scores that in the end mean the modifiers we will roll, just one number that have all those meaning
Just saying that I don't think that scores being different to modifiers is a great flaw to the d20 RPGs, just that simplifying this could be much more friendly and wellcoming to new, and maybe old players
Then you'd have to allow +4.5's etc, because after you hit +4 it's supposed to take two boosts to get you to +5. Fractions are icky.