This is the biggest fault of LBP IMO. Much as I wish they had kept to the original game design of creating in-game, the physics solution has created a lot of frustration and killed a lot of gameplay momentum for the wider audience and what has done most to limit sales and interest. If a choice between launching with a more traditional platform mechanic, certainly in the jumping, or launching with in-game creation, I think the former would be the better option.
This may tie back to the KZ2 control scheme discussion. Most users may prefer direct and responsive control of their puppet with little physics strings attached.