What keeps powered armour from practical service?

How long until Goliath-style powered armour becomes practical?

No date is offered; practical suits depend on better power supply, batteries, recharging and actuator efficiency.

The main obstacle is supplying enough energy for the capabilities a powered suit would provide. Better batteries, ways to recover energy from human movement and practical recharging are all proposed requirements. Efficient electric actuators would also be necessary. The energy requirement has to be weighed against the capability the wearer gains.