The problem is the energy dissipation and source. Yes, it sounds nice, but it is - if we abstract a goal like Doc Ocs octopode tentacles - comparable with an energy intake of 120.000 watts at least. This means around 34 times the energy a one-phase wiring on European households can sustain (around 3400-3500W intake on the device itself plus losses through wiring and other aspects on 16A, as this means a limit of 3680W permanently - short time can be higher through inductive loads).
Throwing cars around and moving at the similar time with a speed high enough to catch bullets, there's multiple assets and factors: concept of mass * speed equivalent which has to get put in, concept of lever-arm laws which means if it gets longer it needs an reinforced base (near the attachment) due to the longer leverage and as such higher stress, as well as it needs ways stronger movement parts near the mount, and last but not least: you need to be stable enough to withstand the leverage stress loads on your body.
If as example you have a reinforced biomechanic exoskeleton attached to yourself, you can improve your own capabilities, as it works as a reinforcement and enhancement through additional linear motors or hydraulics. But it ain't as fast as you are in this concept, as its movements are -either- strong -or- fast, not both. Even your biological body uses different tissue concepts in muscles to sustain both sorts of movement stress: high load and fast movement / impulses.
I could write you an essay about it and where the logical flaws appear, but as I am actually planning and partly constructing my next big project (basically a big canidae robot - yes, fuckable is one of the aspects I wish it to possess, but also power and speed), it requires a sort of balance. Or an energy puffer system which allows a slower increasing of high pressure over time, like an compressor - and a faster release of this in times of high speed or energy output needed. ?
There are enough ways to sustain this but at the end the kinetic energy laws still apply and if I build something which can move at high speed and sustain compensation to aerodynamic losses, friction losses and energy transmitting losses (basically the transition between electronic, mechanic (linear, rotational), transfer of energy, cooling of as example combustion based parts, energy storage and so on), it's still a compromise.
The human body works at the background without sports at around 100 watts permanently. And even as it is highly inefficient compared to electric motor systems (around 25 to 35% of input-output-efficiency), it's still more efficient in total than any robot build which needs several kilowatt peak power input to generate the same flexibility and multi-axis mobility / power. ?
With 100 watts permanently even the processor unit to sustain comparable (primitive) AI based calculations ain't sufficiently supported, haha.
