(As an aside, I find the code-signing in OSX to be pretty crooked -- charging $100/year just to allow people with default settings to run your executables seems pretty sketchy. If it really was about security, I would expect at most a one-time fee, with Apple reserving the right to revoke your key if your programs contain malware.)
It really is about security. You have to ID yourself to get in. If you write malware, Apple has a kill switch they can enable to kill all your apps everywhere, and law enforcement has at least the start of a trail to follow.
I really want Windows to switch to this model! I cringe every time I download an unsigned installer. Even Free Software (Free as in Freedom) developers manage to pay for a cert.
But the current structure makes zero sense.
But a compiler generally received improvements from each of those updates.
A certificate does not; in fact it's quite the opposite, paying an annual fee merely prevents the certificate from being disabled.
I say none of that to justify the overall notion of a paid developer program, but it's wrong to characterise it as just security signing.
Although, now that I think about it, I do pay yearly for certificates for my website - although not $99 :)