It never ceases to amaze me how posts of slave vs sub always turn to discussions of abuse and how the word slave is degrading because of our history of slavery. Let's take a look at the official definition of slave:
# One bound in servitude to a person or household.
# One who is abjectly subservient to a specified person or influence.
Well those two definitions are who I am. They describe my station in life exactly. Therefore Master has every right to call me His slave.
On the other hand, submissive... Well, that's not even a noun. Should we therefore find another word for those who enjoy submitting to another?
I also wonder why you never see similar discussions about Dom vs Master. If you follow the logic of the arguments against the word slave, then Master shouldn't be used either.
What it comes down to is this: As humans we all enjoy the feeling of belonging to something and create labels to signify this. We're husbands, wives, mothers, fathers, slaves, subs, Doms and more.
It's hard enough to find a place in this lifestyle without having others put you down for something like a label.