Ignoring for a moment all the adware that doesn't install toolbars -- superfish doesn't -- you seem to have no idea about actual users. Most people would not notice an extra toolbar, or would think it's part of the default browser.
Not knowing how to repair something can result in a form of learned helplessness, a belief that you are less of something than someone else.
There are efforts to show people that they don't need to buy a new computer, or install software that intentionally limits what their computer can do, or pretends to fix it for a fee. Even the programs that actually work to remove these kinds of threats (including AdAware and SD Search and Destroy) can blur the distinction between actions that are necessary to repair the problem and things that are a different kind of nuisance but not directly a threat to the operation of the computer (like tracking cookies). Software that makes installing it to use it optional is preferred, as the ongoing monitoring can often tax the computer as badly as the software being removed. (Note I'm talking only about anti-adware software here, not general anti-virus software.)
I would love to give a better option than re-install your operating system all of your software, and even that is often a difficult option since the re-installation mediums aren't even shipped with the computer in many cases. I don't want to direct a person to a service where they take the computer to be fixed that often charges more than seems fair for the hands-off approach they take to re-imaging.
Oh, on your last part, I've encountered more than one laptop where all of the installed browsers had been limited to a fraction of the screen being readable due to the number of toolbars, and general search engines being inaccessible or unusable due to the number of injection adds and popups.
Most adware is toolbar free. The only way a user would know the adware exists is by going to their extensions list.
And even now, that isn't the case anymore. More and more adware is moving over to being exclusively EXE based and proxying all HTTP traffic, or using DLLs, or doing something outside of the browser. The disclosures for the ads often times don't actually point to the name of the installed software.
I would agree that users with adware are less tech literate (sometimes), but the install screens are made to specifically trick people into installing.