The things you say are true, dear duck slayer. Attributes like strength do matter more than knowledge on hauling things, but still a small increase in speed, as the hauling skill increases is justified. See, there is a thousand ways to carry a statue, some more and some less effective in terms of speed. If you were to carry a statue of bigger size for the first time you would be rather slow, due to the inability to grasp the thing on the correct spots, as well as your fear to break it. As you grow more experienced in the moving business you develop more confidence and also you get to learn the tricks and trades of hauling which can increase your speed immensely, not on terms of strength though, but on terms of your mind.
I agree the hauling skill should NOT increase speed exponantially, but rather it should aid the strength skill maybe by a fraction of the strength.
To clarify what i mean i shall show you Urist McHauleyhaul. A rather strong fella, he is ready for action. He has no hauling skill though :/. So the speed of hauling is defined by the weight of the item against the strength of Urist McHauleyhaul. As he increases his skill he gets speed bonuses in matter like this (for example, the numbers should probably be tweaked): Str * 1,(SKILLLEVEL*0,0625)
This would be a slight boost at most, but once legendary it would double the movement speed as 0,0625 is 1 divided by 16, and there is 16 skill levels.
So its Weight/Strength*1,(SL*0,625)
Hmm, I hope it is understandable...