There's no consistency or logic to the Force or how it works in Star Wars. All we can ask is that it behaves somewhat consistently within a specific property (ie: a game or novel series), etc. though I suppose really we should say gameplay is king, story comes second, so whatever works.
In the movies, it doesn't seem to work that way... old people and cyborgs can be pretty darned powerful. And sure, we can say people seem to get weaker from the PT to the OT, but I think that's because the OT was made in the late 70's and early 80's and Lucas' style and audience expectations had changed by the time the PT was created. The video games have always been more "over the top" with the use of the Force than the movies (and to that end, the PT was just "catching up" to the EU).
Last edited by Kurgan; 10-17-2011 at 10:30 PM.