The big advantage of Office 365 is if you want to use Outlook as your client on your PC. Outlook works best when using the EAS protocol to talk to the mail server. Hotmail doesn't support EAS for desktop clients. (Strangely, it does support it for mobile clients.) So you have to use IMAP on the desktop, which doesn't work as well, and also doesn't give you task and calendar sync. EAS enables the full vision of cloud email, since your phone and desktop Outlook client will always be magically fully synced. So Outlook on the desktop doesn't go well with Hotmail.
If you are happy using the Hotmail web client on your desktop (and plan to always be connected to the Internet), you won't have this sync problem, and so you would have no reason to subscribe to Office 365 or equivalent.