Why would I possibly wish to upgrade to Windows 10 from Windows 7?
No reason. If Win 7 is doing what you want, you do NOT want to upgrade, at least not until 2020 when extended support for Win 7 ends.
Win 10 will NOT be free for Win 7 users -- only Win 8 users get the break, because they're suffering.
I have half a dozen Win 7 systems, and they're staying at Win 7 for the next 5 years, barring something that I absolutely need, and that will only run on Win 10.