I have two of these and use them.
Whilst I have nothing of real value in my bag, I have a lot of real inconvenience if my chargers, cables, notes, etc. are stolen en-route to a programme. (And yes, if there were room in my carry-on, I would take them with me on-board).
I had my luggage damaged a couple of years ago by a thief who took advantage of a small unlocked zipper compartment - they unzipped it and cut through the lining inside the pocket to access the main compartment. Nothing of value, so nothing taken. However, the bag was wrecked and I didn't discover the attempted theft until repacking sometime later.
I always lock my bag - if they have to struggle to get in, they may just move to an easier target.