You are partially correct that the software update is not required, however you are wrong that the instructions don't mention it. I attached the instructions in an earlier post which at the bottom clearly state that programming is necessary. The programming also allows you to use the back-up camera to zoom in to facilitate lining up the hitch ball with the trailer. I would like to see instructions that state the TSC will function without the update. The software update specifically address how the stability control will react to compensate for trailer sway. Will DSC continue to function without the update, of course, it just won't work as optimal as possible. You are correct that TSC is part of the DSC programming, however it is not inherently active. I will have to find the article confirming this and post it so there is no confusion. If you plan on towing a light trailer, or just putting on a bike rack then I wouldn't bother with the update. If you are towing a boat or anything above 5000 lbs. I would strongly recommend it.

__________________
'12 E92 M3 ZCP Stage 2 Tune, Exhaust, Test pipes, GTS DCT Software
'07 E70 4.8i
'07 E92 335i FBO+Meth M3 Suspension Swap and much more 505hp 564 lb/ft tq (Sold)
'89 E30 325i (Retired with 230,000 miles )