I understand that 1p2c is optimal, but I think a 1p1c option would be nice for those who would want to try that instead, and It'd keep the game's speedruns fresh and new.

This topic comes up every so often and is likely not going to change. Generally 1p1c runs are less interesting to most people, and there is little to no interest of people actually running it. You are more than welcome to run 1p1c, but an entirely new category for that is not needed. Pretty much every time this is brought up nobody does a run.

Here are some further details on this topic: https://docs.google.com/document/d/1DW3UaaQTXirUdvitQFw3BSsjOWNX_136Aiqjxd0npss/edit?usp=sharing