but why certain headphones designed to have high / low impedance, or what makes headphones have high / low impedance?
The final impedance is a balancing act. For a conventional magnetic design (with a wound voice coil) the designer needs to generate enough motive force to drive the transducer. In a headphone the mass of the coil may be a significant part of the moving mass, more mass means less efficient, and a host of other things to consider. A low impedance transducer may have thicker wire and fewer turns for the same mass as a high impedance design with thinner wire and more turns. But the force is the current times the number of turns. Inductance goes up with the square. So there is a non-linear relationship. A low resistance design will have more current flowing for a given voltage than a high resistance design, but the high resistance design can get better motive force from more turns. And so it goes. Planar designs don't get the advantage of multiple turns due to their geometry. They need lots of current flowing, so low resistance, but high currents is a given. There is a whole mess of non-linear competing trade-offs, and the designer has to navigate through them, constrained by the requirements of the product.
There is no right choice, and a designer will balance a whole range of options, including use case, into the design. A higher resistance design
probably gets the designer more options and freedom than low resistance designs. But it may not be possible to hit the needed sensitivity targets, and so on. YMMV.