Satoshi Nakamoto envisioned micropayments in his very first post

http://p2pfoundation.ning.com/forum/topics/bitcoin-open-source

Satoshi mentions micropayments near the beginning,

Banks must be trusted to hold our money and transfer it electronically, but they lend it out in waves of credit bubbles with barely a fraction in reserve. We have to trust them with our privacy, trust them not to let identity thieves drain our accounts. Their massive overhead costs make micropayments impossible.

And mentions micropayments near the end of the article again.

Any owner could try to re-spend an already spent coin by signing it again to another owner. The usual solution is for a trusted company with a central database to check for double-spending, but that just gets back to the trust model. In its central position, the company can override the users, and the fees needed to support the company make micropayments impractical.

It's interesting that his layer 1 is not suitable for microtransactions and that he mentioned it twice on his very first post. Micropayments have great potential and Satoshi knew it.