Maybe instead of a vast conspiracy, it's because LiFePO4 batteries have a much lower energy density? They can be charged much faster, but would you carry a 200W power brick to take advantage of it?
Lithium based ultracaps have on the order of 10% of the energy density of Li-Ion batteries. Would you carry a laptop that lasted 30 minutes per charge?
Most people will have their batteries replaced if it every stops holding a charge. Seems like a fair tradeoff to have devices last 30% longer per charge.