Well technically it would still be possible if the fees were a lot smaller, but that's mostly due to spammers filling up blocks and forcing fees higher, which gets everyone sending higher fees, etc. It's not like there's much that can be done beyond that aside from increasing block size really. More transactions with fees still gives roughly a similar return, with enough volume it all works out properly.
I don't understand why people are blaming spammers.
It should not matter the number of transactions, but the value of the fee being paid.
If "spammers" are paying >= $0.10, then they are not spammers.
Miners should (and probably do) discard transactions paying < $0.10.
Spammers don't matter that much. Micropayments were always going to be impractical in this PoW system.
Satoshi doesn't have to be right about everything. He produced something great, that's all we need to know - after that, what matters is what happens to it, not what he believed would happen to it.
The point is that Bitcoin gives people responsibility for their finances while banks take that responsibility. Therefore, banks can give the option of paying microtransactions while Bitcoin can't - banks can offer fees as a percentage rather than an amount. Since Bitcoin's fees don't increase very much with an increased amount of Bitcoin being sent, it means that what you pay is low for large amounts and will always be high for low amounts.