Lightning channels would ABSOLUTELY be bigger if the fiat price was lower.

Consider that locking funds into a Lightning channel, especially if your goal is to be routing node, is both an opportunity cost and a security risk.

An opportunity cost, because there are other things you could be doing with those funds.

A security risk because your keys are stored "hot."

The more purchasing power you have with those same sats, the more things you could possibly be using them for other than locking them into a Lightning channel AND the more worried you will be about having the keys controlling those funds on an internet connected device.