1. desirability to look at content more closely
2. see above
3. see above
4. see above
5. see above
2. see above
3. see above
4. see above
5. see above
1. I'm old enough to need reading glasses. 2. etc.
(Yes, people do lend their devices.)
If you're not providing a better experience than a fully working desktop site, then you shouldn't attempt responsive design at all and let mobile users use a non-targeted but working site. I only shut of user-scaling on sites where the targeted mobile experience is better than a scaled fully-working desktop layout.