You are welcome to make all kinds of suggestions and new ideas here for Linux Mint, and you're very much appreciated for it. We pool ideas from here and the Community site and take those to the Linux Mint developers for considering. Ideas like default programs to include, new programs to develop, ways to spread word about Linux Mint, ideas for partnering with other projects or vendors, and so and so on. Ideas for the Cinnamon developers however, go to the Cinnamon development site.
That might sound a bit blunt and final, but we've given it good consideration together with the development team. Cinnamon is being developed by developers from all kinds of Linux and BSD distros. It's not just Linux Mint anymore that Cinnamon runs on--far from it in fact! So all these developers, from all these distros, they have to work together somehow and keep track what development has been done and what new ideas are there to consider to work on. The Cinnamon developers use GitHub for that. That's why we want you to post ideas there.
This is no different from you having ideas that would require programming on KDE, MATE, or Xfce--we would ask you to post those ideas on the website those developers use as well instead of posting them here. These desktop environments are developed in the same way as Cinnamon--by a larger team of mostly volunteer developers using various Linux and BSD distros, that come together in one place to do the programming together.