Just like in a year or two you will start to see more appendages than just two arms on humanoids.
A hub motor for each leg adds some weight, but you get a rolling mode on flat terrain with great range.
At the same time you keep obstacle climbing mode with stationary wheels, and can use the leg actuators as shock absorbers and obstacle avoidance on a bumpy path. Best of both worlds, with a new software challenge.
Literally we have a very old saying that is "don't reinvent the wheel" and yet people persist in doing so, when an already near optimal design exists.
I'm not saying don't do anything new and novel but that if a large portion of the design has already been done for you and you can improve it, like this company has done (wheels on the end of legs!), why not try that first and see if it works before starting over.
If it were possible to make legged robots with the same fine motor control and dexterity as human legs, let alone four-legged animals' legs, we'd be way ahead of where we are right now in mobile robotics. We can't.