Thanks for trying it, and yes this is the sort of thing that keeps me up at night! I feel like the traditional snake mode is more interesting and rewarding gameplay, but at the same time understand it's more tedious and some people would prefer to play with the mouse.
My current plan is to add bonuses that are disabled in mouse snake mode. They might give you extra coins, or may just add score (but score could be tied to unlocking things in-game, so this would be a real bonus). For instance, one bonus would be for making a path without your snake ever overlapping itself.
The idea would basically be that the traditional snake mode is the "main" gameplay mode, and you should play it to unlock progress in the game, but that the mouse snake will be an optional more casual option for a quick game or to try out a new strategy.