casascius,

It is already too late. Bech32 is used in the wild and reversing it would make much more mess than keeping it. And I personally believe this is a much cleaner solution than the withdrawn BIP142 https://github.com/bitcoin/bips/blob/master/bip-0142.mediawiki (addresses starting with letters? Come on)

If you mess up "1" and lowercase "l", the address will be invalid, so no real danger with confusing them. Yes, this is probably not the best what could have been designed but everything else is an improvement.

And you know that you can use bech32 all capitals?