I literally have no objective reason (is there truly such a thing?). Just my opinion. Having a code contain 1s and lowercase Ls simultaneously by design is, in my opinion, an obvious UX nightmare that Satoshi did well to explicitly avoid and hardly needed to explain because the potential for confusion requires little such explanation. And the fewer charts you have to memorize to understand cryptocurrency today, the better. Again, my off-the-cuff opinion with zero research referenced because I think this is obvious.
Having two characters BC represent Bitcoin also feels political, as though it is an effort to pretend that there arent alt coins with significant merit. If Bitcoins contribution to the world is a technical proof of concept of currency on a blockchain with a low priority on user experience so someone else can carry the win across the finish line, so be it Ive structured a few projects like that and still considered them valuable successes.
It is not too late to make the prefix 3 characters, the world at large has barely heard of this new address format let alone bought in to it.
I will be happy to use Bech32 if I need to. I am happy it lets me print it in uppercase and that alone solves my issue with L and 1, and I trust that auto-substituting 0 vs O is an auto correction that UIs can safely and easily implement regardless of recommendations. I am satisfied that in the long run, alt coins will satisfy the market demand for a quality user experience if and when the original project fails to. I love Bitcoin (a feeling I will admit I am caught up in) and hate seeing us leave easy-to-solve pain points on the table as opportunities for alt coin teams to look brilliant for fixing.