I don’t see any necessity to change the firmware on a home router. All people need to do is change the default encryption layer and password and do as you say, write the password on a piece of tape underneath the router.
I was making the recommendation to those who like to tinker. The default router firmwares are generally stable, but you’re at the mercy of the manufacturer as to what features are enabled. Default Linksys firmware has very limited content filtering, but install DD-WRT and you have more content filtering than you could possibly imagine!