To be fair, Linux Mint is based off Ubuntu, thus it used to
adhere to Ubuntu's release schedule and support dates. It will still follow the support date plan laid out by Ubuntu, but the upgrade method is now altered beginning with LM17. So it wasn't trying to purposely annoying users with 6 month upgrade paths, and you didn't even need to do that. You've always had the choice to use the current LTS and save yourself from the 6 month release cycle versions.
That being siad, one should always stick to these basic rules of thumb -
- 1) If you enjoy being on the "latest and greatest" Linux software and you're on an Ubuntu based distro, just get used to upgrading every 6 months. This is what I do, but it's optional.
2) If you want stability and long-term support, always stick with the LTS versions.
NOTE - Now, If you're on LM17, this will be a much easier process (push-button in-place upgrade), but I believe it's still
optional on whether you upgrade or not.