Earlier quoted context omitted.
99% of crypto would work just fine if you appended an OTR-like protocol over the top of email. First email is "hey we're interested in blah..." and is sent in the clear. Then have the message window change color as subsequent emails get the protocol more secured.
I hate color coding. I'm in the 8-12% of men that have red-green deficient vision. You can use 10% as a rule of thumb. If I'm not mistaken in my probability math, that means in a group of 5 men, there is a 50% chance one of them is "color blind." Yet the world insists on using red/green as bad/good indicators. Drives me nuts.
People who can't distinguish vivid reds/greens are much rarer. (If 10% of men couldn't separate red from green at the stoplight, we'd have noticed a long time ago.)
I agree we should include everyone, of course, which is why there should also be patterns, shapes, and sound to assist, I'm just saying color coding is not some collossal mistake.
(Also, your math is off if you're assuming a 10% base rate. To have at least a 50% chance of 1 person in a group of men being color blind, you need 7 men. 1-(.9^7)= 52%.)