I wonder why people sceptical with this tools when they dont event know yet evout this 
Because most of the time, it's crackpot of theories that actually already utilise something that already works, then tries to rebrand it under a different name and then make a quick buck and presteige off of it.
Alex Chiu's "Super IChing" for example, was nothing more than ripping off existing Chinese material and then putting their own interpretation onto it before anyone realised more about it (it was done before Chinese material was more easily accessible in the West online due to non-conforming standardisation to non-western languages online at that time, where there was multiple of ways to enter Chinese characters into the computer, but none of them when entered into something else showed up as the same thing until this was standardised later on. This made it difficult to locate material easily for a very long time).
Here, we have a mish-mash of existing systems that have been cobbled together and then, once again, branded as something new. The thing is, it "reads" as something different, to a Western audience. Especially one that has not been exposed to such systems before. So it sounds excellent and new.
However, if you have experience with such systems before, you will quickly notice flaws with what the system (Human Design in this case) is and can tell that it is not anything near to what it claims to be or can do.
Care is often advised in such instances, as even in Chinese metaphysics, there are systems that also do something similar by cobbling other systems together and then producing information from it to do a reading. The only issue is, if you are already using existing systems, are you really doing something new? Or just rebadging something else and then selling it on under a different name?
A quick examination of what its purported charts and proposed readings, shows that it has some aspects it gets right, but others not really. And of course, much of these systems also do not really predict anything concrete, instead using a general catch all approach to fool those interested in it that it seems to have got stuff right, which is nothing more than kindergarten level of metaphysics (if that). This is often seen done by charlatans who are covering their lies and impotency through flowery words, etc. to utilise a connection between them and the querent to avoid being brought up on lack of details. This is not unique to Western systems, but any charlatan using Chinese metaphysics as well.
All in all, nothing new.