Paying people more money is more expensive; giving people ownership is less costly. Employee owned shares encourage employees to work better. It also gives them a louder voice in how things are done.
And what if I hire workers to build me a house - should they be entitled to parts of the house after they build it? Or what if they absolute want to put marble into the bathroom, but I don't? Should they be entitled to put marble, because after all they are doing the work?
Meaning what is wrong with making a contract and fulfilling it? You do work x for me, I give you money y in return? Why make things more complicated?