I agree.
Improving the value of consensus 'Late Round Picks' could go a long way in improving those 'niche' positions, as you suggested with Returners.
I think Arm Strength should improve... and decline... as well. It should improve early and decline late, but it shouldn't be huge. Something like a +5/-5 from the Generation Point. So a QB could start with a 75 Arm Strength, move to 80 by his 3rd or 4th Season... and near the end of his career fall off to 70.
You see a lot of guys get gains in Strength, and we all see QBs lose that arm late. Even Elway in his final Season, while still having a Stronger Arm than 99% of the League, didn't have as strong an arm as he did 5 years in. So the explains why it should Decrease.
And guys like Brady and Brees showed improved Strength... some feel if Tom hadn't gotten a stronger arm he'd never have become the QB he became.
Now this does suggest that many never really improve it... which is fine, most would fall in that +1/-1 Range, but some guys could have a greater swing.
Even if this really just affected a few guys in any meaningful way, it could have a major impact felt for multiple seasons.