casascius, with all due respect, I dont see any argument here other than sentimental attachment to the appearance of old-style addresses, plus a few relatively minor quibbles about confusable characters.
I will address the latter first, since it is a technical issue. Any selection of characters for such an application will always involve tradeoffs of excluding worse confusable pairs, whilst regrettably tolerating some less confusable pairs. Of course, making that distinction cannot be what Id call an exact science. BIP 173 set forth its rationale on this point; do you have any objective reason to contradict the research it cites?
As for the flavor, as you put it, I dont mean to be derogatory. You yourself characterize it as a matter of affection. But its just that.
A colourable argument might be here interjected on grounds of marketing. But really, from the coldest marketing perspective, how many actual Bitcoin users do you propose to be attracted by the look of the addresses? You speak rather derisively of a whole legion of Bitcoiners who scan URI-less QR codes at PAL resolution with VHS cameras and 6502 processors are leading the charge to change Bitcoin so they never have to upgrade past the pre-Internet as they send their Bitcoins off a 64K floppy disk. But I think here, you have it backwards: Persons fixated on the look of the address will be a marginal minority, frankly stuck in the past and resistant to technological improvements. I suspect that unfortunately, most Bitcoin users care neither about the look of the address, nor about its technical functionalityin other words, they agree neither with you nor with me. They scan QR codes, they think about money, and as most people generally, they contentedly chew their cud in the Coinbase corral. The form and function of Bitcoin addresses is really a non-issue here. Im more worried about how many dont care about decentralization, fungibility, permissionlessness, privacyfreedom.
I will meet you halfway in positing that the human-readable prefix btc would be better than bc, at the expense of an extra character which transmits no data. The string btc1 now carries some rotten baggage; but Bech32 antedates that wretched idiocy and will long outlive it, just as the same applies with its use of the BCH error detection algorithm which is its namesake. btc1 with the separator also seems an homage to the old-style P2PKH addresses; indeed, I have a tiny suspicion that the reasons for choosing 1 as a separator were not wholly technical. That warms my heart, and might even mollify you a bit. I suppose bc1 sort of does that, too; and hey, it saves a character! Of course, this is an issue only with the specification of Bech32 addresses for Bitcoin, and not with the Bech32 format itself.
Returning to technical issues:
I think you far underestimate the difficulties caused by mixed case, especially for persons accustomed to non-Latin writing systemsor for anybody with fingers for typing, plus a labile human central nervous system which cannot reliably process and transmit patternless pseudorandom data at all. The human brain finds it easy to follow the patterns natural-language capitalization rules; to add capitalization to gibberish only adds the dimension of an extra variable to keep on the squishy wetware mental stack. For your anecdote of being just fine and dandy with the mixed case, I will raise you my anecdote that I hate it, I cant handle itI find it absurdly frustrating and error-prone. Surely an expert in human-computer interaction will weigh in here; do you wish to place bets (gentlemens wager) on whose side that evaluation will support?
Satoshi was a genius. But lets admit it: He had a few quirks. The propensity to use (truncated double-)SHA256 where inappropriate is one of them; and Bech32s change of checksum removes one of those niggling little flaws which always irritated me amidst such an ingenious creation. And that base58 you so adorewell, I love it not; and I doubt Im alone there. I think there are exactly three people in the world who are enamoured of base58 for use in a binary-to-ASCII encoding system; and now we have enumerated two of them, you and Satoshi.
Ill admit, as a C programmer, I am a tiny bit annoyed by the Bech32 choice of alphabet. Its not in ASCII order! The stupendous inconvenience of a lookup table is required for decoding, rather than simple arithmetic from offsets as in RFC4648 base32 alphabet! Horrors! Well, I do suppose that I, too, can be annoyed by Bech32s kindly consideration of squishy humans and their errors. I recognize that regrettably, I have just made what is perhaps overall the single most myopic anti-Bech32 argument ever yet proposed.
I will here truncate this flow of words, for I neednt here (double-SHA256) rehash the rationale of Bech32 design choices. BIP 173 already did that, and did so at least adequately to persuade me. Well, it did more than that: The Bech32 format is so superior technically that it made me realize, on a deeply personal level, just how excited I can be made by an address format.[1] To be fair, I there mirror your pained nostalgia for the old format. Also to be fair, I admit that I am odd.
Please give Bech32 a chance to grow on you a bit. If you keep an open mind and try it for awhile without bias, I think it will win you over.
1. My regards to Pieter Wuille and Greg Maxwell: I can tell that an excruciatingly detailed thought process about Bitcoin address formats went into that bit of engineering. Somebody stayed up in the dark wee hours, pondering the philosophy of Bitcoin address formats. Somebody aspired to consummate perfection in the art of Bitcoin address formats. Well, you are probably also odd. Coming from me, take that as a compliment.