Yes, but it does give you extra options when you're moving to lower areas. Let's take the airport vid about smart as an example. If you jump over the railing you will land on some kind of plateau. A medium or heavy can get over the railing, but not on the plateau, but with increased speed they might reach it. (not sure if this is true, it's just an example.
I'll rephrase what I wanted to say initially. With increased speed, some routes will become more viable for medium and heavies.
33% speed increase was just a rough number. I should clarify. Sprint speed would be increased more like by 10%, mantling speeds and the like would be increased by 33%. The speed increase does NOT affect purely physics related activities. Just because you can claim over a wall faster doesn't mean you can magically move through the air faster. Inertia from running affect the speed of your movement in the air, of course, but that would only be a 10% increase because you're only moving 10%. But climbing up onto the ledge you grabbed onto on the other side would be 33% faster due to the ease at which you can do it with a hand free.
Sure, heavies and mediums could use one-handed weapons to help counter their increased weight and decreased speed, but in doing so they sacrifice sheer firepower, something that those two bodytypes are more focused towards. A heavy might be bearing down on you slightly faster than you expected, but he's not going to be particularly scary with just a pistol in his hand. :V
Just like a light would be incredibly agile with just a pistol, able to reach objectives and flank opponents easily. Alternatively, he could take an SMG to increase is firepower for holding an objective once he has it. Checks and balances. Pros and cons.