I don't find pointing my phone at a QR code and hitting the send button particularly hard... But that's just me...

This is just the beginning. Bitcoin will be evolving more and more

You're skipping a few steps to get to that point.

For the average CC user, its all baked into social norms so signing up for a card is trivial.

For Bitcoin, you have to train tech-illiterate people from square one, starting from how to buy bitcoin.
Most people don't even know how to scan a QR code or what Two-Factor Authentication is.

Any one willing to learn the skills can come up with a client. If it is easy to use and solves an issue then it will become popular. Personally I feel more secure with the QT client so that is where I store my coins.

What about a wallet app that uses iphone's thumbprint sensor to verify a send?  (now that Apple is more open to bitcoin)

I think the answer is an online wallet + phone. Ie coinbase and the coinbase app that lets you scan a code/adress and u can then verify the transaction via you phone.

A physical card makes no sense in my eyes.

Copying a CC functionality is just going to create a crappy CC that is more complicated than a standard CC.

Yep. More things to carry and protect along with more things that you have to worry over security seems like a step back.

If a bitcoin private key was encoded on to a smart card chip on a credit card style plastic card, what would happen if you lost the card? I guess that would mean anyone could go around signing transactions with your private key. People lose their (physical)wallets or have them stolen often enough that this would be a real concern.

I guess one solution would be to load only very small amounts you could afford to lose on the wallet that has the private key attached to the smart card. The pin system is interesting too, would you simply be able to set your own pin on the smart card after loading it with money? Is that possible. I'm guessing the way it works now is that your pin is verified by your credit card company. That obviously wouldn't work for bitcoin unless you were using a centralised service like circle or something similar.

A theoretical solution I can think about, is as Card, with a small power source, a NFC Reader, a small Display and a NumPad.

You get Address and amount over NFC, check amount on Display, type in your PIN, Card generates Transaction and send it to the Transaction device.

So, it's swipe, check, Password, swipe, which should be user-friendly enough and much more secure, than typing a PIN into a foreign machine like with credit Cards.