I have a bitcoin debit card. It works just fine thanks. I can spend it anywhere that accepts a card.
Bitcoin from my wallet is being spent. It is increasing in value while i don't spend it, because it is in bitcoin. It is no different than an American using their cc in europe.
Exactly, they aren't. Coinbase owns the private keys, thus the bitcoin.
It utterly contradicts the title of Bitcoin's white paper:
Bitcoin: A Peer-to-Peer Electronic Cash System
You skipped right over the peer part, even though the word is used twice, and started talking about the cash part.
No matter how you try to spin it, you can't make a future where the vast majority can't control their own private keys sound consistent with Satoshi's vision, or rewrite the public statements Satoshi made about how Bitcoin should scale.