Rating players by position makes perfect sense. Kickers are not expected to do anything but kick, if they can tackle that is a bonus but the hope is that you would never need them to tackle anyone. It makes no sense to rate a kicker with 99 Kick Power and Accuracy, as well as 99 Awareness as anything but a 99 OVR, if you line him up at any other position then his rating will drop fast.
The only way your proposal makes sense is if players were divided by role: OL, DL, LB, DB, etc. Even then you'd still like to see how much better they stack up at different positions so position ratings would still be needed. I feel that doing this would make things simpler in determining who is the better Offensive Lineman/Defensive Lineman, but would be useless in determining whether or not they would work at a certain position along the Offensive or Defensive line, DT are very different from DEs, OT are different from OG, which are significantly different from Centers. Basically you are arguing for a simplistic rating system that doesn't actually do anything to improve how players are evaluated. Football is full of specialized position which really limits the ability to rate players as though they are all equal.
I would be in favor of toning down ratings (i.e. FIFA), they had toned down players at the beginning of Ultimate Team this year and it really made you focus on your strategy (you had to consider chemistry because you couldn't just stack the OL and run on them, at least not at the beginning). But even in that situation a Kicker with 99 in the 3 categories that they have for measuring Kicking ability should be a 99 Overall.