See, I told you I'd get resistance
IE already has its protected mode and enhanced protected mode sandboxes, Flash runs in its own sandbox as well, so does Java and then you also have things like DEP, ASLR etc. Moreover even admin users since Vista cannot modify files in system directories without agreeing to the UAC prompt. Of course despite this systems still get infected due to bugs in one or more layers but mainly because people have a tendency to click on whatever the heck they want and ignore all warnings that keep them from viewing
dancing bunnies or
dancing pigs or dancing babies or whatever (apparently
nothing trumps cutesy crap!) That said, I do agree with your advice in general about running as a normal user account, but IRL there are always caveats.
I did simplify my explanation a bit as my post was rambling on a quite bit. I had my audience in mind, I'm not going to write an essay on security practices here
I know there's some paltry privilege separation between an admin user and an admin user elevated with UAC, created to deal with the issue of everyone and their mother running admin accounts, I know IE, flash and java are all trying to cover their exploits as they happen and create proactive defenses. But I've had a virus bypass EPM, exploit flash and in an admin account it was able to deactivate and destroy windows defender so sufficiently that I could not fix it. There is indeed privilege separation in admin accounts, but any program run from an admin account even without elevation still has more power than a standard account. I've encountered several programs that don't request UAC elevation because they use the manifest to request "highest available privileges"- these programs can operate fine under the "lower privileged" unelevated admin account but suffer access errors under a standard account. Luckily, you can simply elevate them manually and they work as expected.
tl;dr yes there are other security measures in place but that's no reason to forgo additional layers of security.
Reasons why people use admin accounts and even turn off UAC:
1. I bet 99% don't even know the difference or don't want to repeatedly see password prompts.
99% of users don't do anything that would actually trigger a UAC prompt on any regular basis. 100% of users should not have been exposed to such a carefree, unsecured environment in the first place.
3. Windows since forever has created admin accounts by default after Setup. Probably they introduced UAC and downgraded admin accounts a bit but did not make user accounts the default because of the reasons above.
Neither does your average Linux distro create your user account for you. The person setting up the computer is assumed to have the knowledge to actually see the installation to completion
But it is true that, because it is the way of things for windows users to simply be admin all the time, OEMs who profess to have set up the computer for you won't dare to ship a computer with a user account.
Changing Windows user (and dev) mentality is a massive undertaking. Think about your average clueless users for a moment, for example family and relatives you often provide unpaid tech support for. That's why I don't quite agree with your assertion that "whatever "active defenses" your AV claims to have, it's not worth paying money for". The better lot among the many anti-malware suites are the best bet to keep such users reasonably safe while not being too intrusive, and I'm resigned to cleaning their PCs of junk (not just malware but toolbars and other trash) regularly for the foreseeable future.
The one ray of hope for me is those few who've moved on to iOS/Android/Windows RT devices for their computing needs.
I actually conducted a real-life experiment once to see how many could survive with a user account. I kid you not, before the week was up I was inundated with irritated and even angry calls about how I had 'broken' their computers, why their computers kept asking for a damn password every so often or why their favourite programs no longer worked, and no matter how much I tried to explain how secure they were now, they just didn't care. When security comes in the way of them actually using their computer, guess what's the first victim?
Where better to inform than on this rather technical forum? I think I've explained what it does, I spelled out the caveats pretty clearly. They know how to do it, likely have some technical aptitude and the ability to understand what they are doing. They know where to come get help and most of all they have to opt into it. It's not like, by reading my post I forcibly alter their PCs forever against their will
Most importantly, I think that 7 and 8 have finally gotten UAC down to a refined level where it in fact *does not* pester you incessantly. It only requests elevation when it should, and a normal user rarely would come up against it. Despite our complaints with the number of programs and devs that which won't slide 100% seamlessly into a standard account, the truth is the solutions are simple and the show stopping problems are infinitely rare- and as power users we are more likely to come into contact with that sort of thing than any normal user.
I too have cleaned many a family friend's computer of malware and then set them up with a standard account. With proper explanation, removal and replacements of poorly behaving programs and a warning to consider what they (or their kids) are trying to do before just typing in the password.. I have had no complaints.
Even myself, the power user that I am, run a standard account. I never used to- until it was pointed out to me that I tolerate it on linux, and not windows? What sense is there in that? And in fact Windows is *better* than linux's sudo because UAC supports biometrics, it's really painless. UAC prompt? Swipe finger on the fingerprint scanner. Boom. (Linux too supports biometrics, but it's unrefined, awful, not actively developed garbage).
Yes, knocking some sense into the windows community is going to be an uphill battle. But this needs to happen; the sooner the better.