Creepers will only breach through walls if they were already previously chasing you.
If you are in your house a lot then it would be annoying if a random creeper that spawns outside blows a hole in the side for no reason.
It would make more sense for creepers to only breach walls if they were running away from them.
It would create more of a "you can run but you can't hide" situation.

Theoretically, turning off the X-Ray setting in the config should already create this behaviour. If this is not the case, let me know and I'll take a deeper look into it!

well yes theoretically but once you close the door they forget you exist

Ah, like that. I think it should be possible to add a variation on the x-ray targeting I currently use, making it so that a creeper needs to see the player to start chasing. I will take a crack at it in due time.

This is now implemented in the next 1.18 release of the mod, version 1.2 when it releases. The default settings keep the current behaviour, but x-ray behavior will be split between xrayStartTargeting and xrayFollowTarget.