An unlimited storage offer is intended to store as much data as you want. The difference is that there is a low natural limit to how much you can drink.
People aren't wrong for storing unlimited amounts of data in the unlimited amount storage space they pay for. They don't have to evaluate if Google's offer makes business sense for it, that's Google's responsibility.
If you offer unlimited and only give 2 drinks / person, you're lying, shame on you. If you drink more than 10 people combined, you're drunk with questionable social compass. When you take more than 100 or even 1000 people, then you are technically correct - the best kind of correct for a sociopath.
How do you know that?
Turn the tables; say that as a customer you agree to a company charging you an unlimited fee each month for a service. Do you think they'd charge just $1 because they 'know' you didn't mean all of your salary?
I think its a little less clear for ISPs where large amounts of data usage is normal for average users but in the case of storage, people dumping petabytes of data they don't even care about is clearly misuse. If the drink place stepped in to stop you after 5 drinks that would probably be false advertising.
Yes maybe Google was wrong about calling it unlimited and now they are fixing that by making it not unlimited. That doesn't change the fact that people were actually misusing it