No mention of this in the UK rule set at least:

https://ukmars.org/contests/contest-rules/micromouse-classic...

And even if you're not pushing off from the walls, additional wheels on the sides of the mouse could help get more traction by running along the walls.

Have there been thoughts to adjust the rules or make a parallel format that increases the amount if opportunity that competitors have to get creative?

Citation? Scratching, marking and damaging walls is not allowed.

(https://ewh.ieee.org/sb/columbus/devry/sacFiles/MicromouseRu...)