It (?:) would allow you to incorporate logic into expressions. There are contexts where only expressions are allowed, such as: - lambdas - DTML expr attributes in which I'd very much like to incorporate tests.
Don't know much about DTML, but believe that being able to put conditionals in lambdas would make the latter much more useful.
The ?: syntax does not introduce any new "functionality" to the language, Yes it does.
Is anything possible with ?: that's impossible without? No --- Python is Turing-equivalent before and after the change. Is anything easier with ?: --- yes. Does this make up for the added complexity? Dunno (see below).
The second qustion I'd ask is, who is this aimed at? It's certainly not aimed at first-time programmers, as I know from experience that the ?: is one of the hardest things to teach people in C (after pointers), Hm. I can't agree.
Strongly agree with the first author --- IME, ?: is very hard to teach. Greg