Not sure what you mean by that. I dont see most people doing that. I see most people holding it like this, or very similar to this. I hold it this way but have my pinky underneath it a lot of times and ive never hit the back button on accident.
Image
----------
I never had that issue either. I guess its just where or how you grab the phone. I love the capacitive buttons and would prefer they get rid of the physical home button though i dont have any issues with the home button either, i just think it looks better without it.
I wouldnt like having buttons that you have to push hard to get them to work. That would irritate me.
This is held at the bottom, move you thumb over to tab something on the screen and it brushes the back button or home button - very annoying. Happened all the time when I had GS2 and also on my Windows phone (Lumia 820) - L820 is a great phone just the sensitive buttons annoy me so much.