S-Check, agree totally.
I ALWAYS belt up when I fly (having once seen that NASA crash test footage with the dummies was enough to convince me if i hadn't been already!)
, and I like to keep a hold of a seatback when moving about the a/c... Like you say, I just keep an eye out for the possible "large person" who may land on me or block the exit come an emergency....!
Reminds me of a quote by John Wiseman, the SAS dude, (about survival kit but also applies here to seatbelts)
The day you'll need it is the day you leave home without it....(or don't wear it etc)"
Sky