When in pedestrian mode, I don't mind what is efectively a polite request to allow someone to pass who is travelling faster than me, or as a warning that someone is coming along: effectively a request to not suddenly dart sideways.
I went for a long long time without a ding a ling (stoppit), and still don't have a bell on one of my bikes (for space/weight saving), but I realised again how useful they can be after one came with my Brompton. It was integrated with the gear shifter, and very small and light, so wasn't worth removing (which I might have done instantly otherwise).
I find a bell most useful on roads - to make some more pedestrians notice me instead of step out in front of me, particularly at the corners of left turns (for me). It doesn't make it safer. It just means I go faster when I reckon there's a high chance that I've been seen. I don't rely on them to hear me, I only change my actions if hearing me as made them turn to look.
So it's a convenience device, not safety device. I'm not ashamed to increase my convenience, within reason. SPARING use of a bell is reasonable.