I've used Debian earlier this year and apt works nicely indeed.
But as to your "Windows Update is a very pale comparison to the "mechanism" built into many (most/all) linux distros" that's simply not true.
It works as least as well as does apt.
"Microsoft only occasionally provides updates to its own software."
Microsoft releases updates every week, more often if needed.
I'd hardly call that "only occasionally". They just don't issue major press releases when going from version 0.0.3.1.18.104.22.168b3 rc1 to 0.0.3.1.22.214.171.124b3 rc2 like Linux groups are wont to.
"someone who has a financial stake in the product, or someone who loves it?"
Neither. That would be someone who has the capability of looking at that product from a distance without emotional or financial attachment.
Your love for Linux clouds your vision so you don't see the shortcomings of the platform (or as I've seen by many Linux zealots actually call those shortcomings strong points).
" I wouldn't enjoy all the extra work, job security, etc if we lived in a Linux world."
You'd have even more work to do as every cracker in the world would use the availability of the source code to find and exploit the holes.
At the moment you get only a few hardcore ones interested at breaking in to juicy corporate LANs and hold them ransom or steal information, but in your ideal world you'd have to deal with script kiddies using hacking kits written by others which is exactly what most attacks on Windows platforms are today (attacks which would almost invariably fail if people weren't listening to anti-Microsoft propaganda and failing to keep their machines up to date be they "don't trust Microsoft".