I only learned after posting that Microsoft has started pushing these as important updates, not optional updates.
Eventually I will migrate a bunch of computers to Win 10, but I will not permit Microsoft to force me to use version 1.0 of their new operating system. My rule with new versions of Windows is to wait until the first service pack comes out before installing. For Win 10, I will either wait until SP1 arrives, or until the free upgrade offer is about to expire.
Microsoft will support Windows 7 until 2020.