Um. When drives didnt park themselves, you wouldn't scratch the disk when it turned on. You would simply lose any data that was in the buffer when you shut down.The read head does NOT touch the platter.. it just comes very very close. Now, you could cause SERIOUS problems if your drive got jarred without it parked, because the read head is out on the platter and could easily do damage.. But it would be just as likely if you jarred the drive while it was running. Old drives were much more easily damaged this way. Its just not really a problem now I find unless you actually drop the thing.
As for the whole not shutting windows down properly. Hmm.. I've had a system for two years now. The hard drive that is in the system has been there for 1.5 years. I have NEVER shut it down properly in the car. NEVER. Bad sector count? ZERO..
I used to run a scandisk regularly just in case.. (mostly worried due to the drive in the car in the first place).. No problems. Not even a single one. Any time I have reloaded windows, it was by choice to try ME, or switch back to 98 etc etc... The system has been shut down many a time in mid boot as well, and still no problems.
Oh, that DOS/Windows format? Same deal. They both just erase the file pointers in the FAT. The data is still there and can be recovered. A low level format will write every sector on the drive to zeros. That usually gets everything (and can kill some drives too, its not recommended by some drive manufacturers, however others provide a tool.. go figure)
In my opinion, shutting the computer down is not necessary. But live by your own experience/inexperience.The shut down controllers however are great to auto start & auto shut the computer down in case you forget to flip the switch.