Here's my fix to 3.5e (house rules):
All light and hvy armor adjusted so the AC and Max Dex total 9. Med armor totals 10.
Armor check penalty is simplified to -1 for all light armor except padded (-0), -2 for all medium armor, and -4 for all hvy armor except full plate (-3 because it's so well made and expensive).
Armor doesn't affect movement rate (but its weight can affect encumberance which does affect movement rate, and I increased the weights of medium and hvy armor to more appropriate levels).
I also reduced sprint to x3 for medium and to x2 (meaning there is no sprint) for heavy armor.
I moved Hide Armor to the light list.
So it looks like:
Padded: AB 1, MD 8, ACP 0
Leather: AB 2, MD 7, ACP -1
St. Leather: AB 3, MD 6, ACP -1
Hide: AC 3, MD 6, ACP -1
Chain Shirt: AB 4, MD 5, ACP -1
Scale: AB 5, MD 5, ACP -2, Wt 40
Chainmail: AB 6, MD 4, ACP -2, Wt 50
Breastplate: AB 6, MD 4, ACP -2, Wt 35
Splint: AB 7, MD 2, ACP -4, Wt 60
Banded: AB 8, MD 1, ACP -4, Wt 70
Half-Plate: AB 8, MD 1, ACP -4, Wt 60
Full Plate: AB 9, MD 0, ACP -3, Wt 70
Given these changes, nobody ever chooses armor based on mobility, though they might consider encumberance and long-term movement (running all night long from a horde of orcs is fatal to heavy armor wearers).
Light armor favors people who magically enhance their DEX. Heavy armor favors people who have little or no DEX modifiers. Medium armor is for the people in between who have some good DEX modifier but not magical enhancement, and maybe don't have super high STR so the lower encumberance helps them too, and they can conceivably be a point of AC higher than they would be in light or heavy armor.
This has balance the playing field and I see all types of armor used in game.
And when the monster horde includes a suit of +3 Banded Mail, the "lets sell it" option is not always the first thing out of everyone's mouth.
True, our acrobatic armoredsaint has shown that maybe heavy armor wearers should get reasonable DEX modifiers, but that would make heavy armor somewhat game-breaking, so I'm willing to sacrifice some reality for game balance.
This kind of balancing would make 4e armors much more palatable, methinks.