Bill Gates would no longer be in the top ten most rich people list.
that should be fine if it's a result of the owner's fault, under other circumstances, if he's a victim of a crime (theft, sabotage, etc), most people will probably think not having a lost-coin recovery mechanism is a flaw.
Some will, certianly. Those people can stick to paypal, or buy insurance. Not that a sum as large as what Bill Gates could hold in bitcoin is insurable, but it might for others. I expect that, eventually, bitcoin banks and similar institutions a la Mybitcoin will have to be insured against liability losses in order to attract and keep customers, but the fees that they charge will have to be low enough to compete with the cost of regular bitcoin transactions, as a well managed personal client with encrypted backups is as good a form of prevention of loss as can be insured against for most people with the good sense to accumulate any notable sum.
Sorry about the long sentence, btw. That's just how long it needed to be.