The music labels are bullies. Bullies take what they can whether it's rightfully theirs or not.
If nobody stands up to them, then they'll bully everybody.
How we access our music after paying for it is none of their business and they shouldn't have a say in it.
What they mostly hate about this is that users of this service will be able to access their music collection from anywhere without the need to repurchase it. Plus, Amazon's cloud is very well backed up and users won't be losing their music collection anymore; not to theft, not to fire or none of the other reasons that caused people in the past to repurchase the same music again and again, benefitting those mobs over and over.