Perfectly lovely adult homes turn instantly to baby-gated eyesores come crawling -- and that's just the start. Raising everything to upper shelving and installing cabinet locks, toilet seat locks, window locks and faucet and door knob protectors and takes hours and hours, and even then you're still chasing after the kid when he starts to climb.
Two words: force fields. They could be installed at every point of possible harm and/or destruction. They could even, later on, protect the walls from finger painting and block the windows from teenage escape in a grounding situation. In the latter case, the technology would need a password-protection option.
And finally, the Holy Grail of busy motherhood.