They're not minor problems. Please don't underestimate the epidemic of hacked sites that are a direct result of end-user unwillingness to upgrade and possibly break their site. This is a problem that can't be solved without significant architectural changes. Customers are more willing to risk getting their websites pwned than to risk an upgrade that may take their site down, so upgrades often aren't done for years.

It's not a small problem, its a huge one, and the primary reason why I can no longer recommend Wordpress.