Paper bitcoins (otherwise known as bitnotes) can be useful too
As with everything else, Bitcoin faces the last mile problem. To transact with it, you need Internet access (just like with Internet banking). Bitnotes can effectively solve this issue if they are issued in a unified way as well as accepted by major Bitcoin payment processors (Bitcoin protobanks) which have physical presence. As to me, the advantages of paper bitcoins heavily outweigh possible drawbacks and problems that could arise. But these may not be possible until governments universally accept Bitcoin as a legit means of payment
How could physical bitcoin (bitnotes, or otherwise) ever be secure? They would be massively easy to counterfeit and anyone accepting one could never be sure they actually own the value denoted by the physical note, because the true ownership of bitcoin is dictated by an electronic ledger. I could hand you a physical bitnote, and then use the private key for the bitcoin it represents and go and spend those bitcoins electronically. You then would not own the bitcoins the note represents, because you have no ability to move them in the blockchain. I don't see a way to ever have a secure physical bitcoin, because the private key dictates ownership, not the physical note.