I'm with you on this. We have a 2004 LS 430, a vehicle I consider as closer to my idea of perfection than any car I've ever owned, as well as a 2004 RX 330 - both with navigation systems. If I were to list my single aggravating item about the car after three years of ownership, it would definitely be the lockout of navigation and telephone features, even if the car is barely rolling forward. There is the obvious distraction factor, but it's certainly no worse than any other of the many distractions a driver faces. So it takes responsibility on the part of the driver to know when to not be distracted, even for a very brief time. Your experience near Orlando has been repeated by me on more occasions than I care to recall. Include me as one of the 50, or however many this turns into.
I have a 2004 LS and use the following fix to get around the lockout. I understand this exact routine won't work with the 2007's but guess there is a similar way to access a secret service menu that will disable the lockout. Eventually someone will discover it and post it on the web. This definitely works for the 2004 LS:
Here are the steps:
1. push the menu button
2. press volume
3. touch the screen in this sequence: top left, bottom left, top left, bottom left
4. this will take you to the override screen
5. press and HOLD override until you hear a beep, and the icon is outlined
6. press back
7. press the map button
You'll now be able to operate the navigation/phone features while the car is in motion. The only drawback is that you'll have to repeat this sequence every time you restart the car...