I don't know if having to use the company luggage is an advantage.
What if I prefer a bigger/smaller thing? And of a different type? KLM CC are supplied with an old type of suitcase that I stopped using some 7 to 8 years ago, when I decided that the trolley type, and then the 4 wheels trolley type was better for me. Plus, they cannot use the company luggage for their personal travel. It means that if you don't live in AMS, and have to commute after the flight (which would be my case since I don't live where my company is based) I'd have to change suitcase or put a fabric cover over it. I kid you not, I saw it.
After all in my opinion it's better to be allowed to chose your own luggage, even if you must pay for it.