Which is apparently what they already did...
What happens when Stan Smith is rated a 3 helmet player when the game ships, and by now he is a 5 helmet player? Too bad, attributes are fixed.
The current set up if perfect - if you don't like the attributes that someone else in the community has assigned, you can just edit them yourself. Too many people seem to think once they've downloaded the teams then they can't change anything themselves.
i wouldn't say "perfect", but it's damn good especially because as you say you can change things you don't like.
what i would like to see, however, is a more flexible approach to skilling.
rather than 1-5 helmet, you can choose what the player is... i.e.: club player, domestic journeyman, associate journeyman, domestic star, international journeyman, international star, all time legend.
based on your selection, it would limit not only the overall points available to skills and attribute, as well as setting a maximum value for individual skills (e.g. limits arm speed so no more county players throwing down 95mph bombs), and also set a limit on how many of the individual skills can be maxed (for their level). e.g. say a domestic journeyman caps any individual skill/attribute at 70% of the bar, but also only three of the skills can reach 70%... for all time legend the max would be 100% and say 10 skills can reach 100%
this would give us much more flexibility, get more realistic skills but should still be pretty simple to implement since it's data configuration in academy to set the skills, and actually no gameplay changes are required since the gameplay should just be pulling the skill levels.