What I didn't really like about he parents comment is that it seems kind of "lazy" not to do your edges. My wife broker her arm recently when a kid fell over in front of her and she couldn't stop quickly. On steep icy terrain this is a concern. That was my true "fly off a cliff edge" example.
The comment seemed like a "I don't wear a helmet because it's uncool" sort of thing...just do your edges occasionally, what's the issue?
Well I did as a racer and still do on my firm snow skis. But there is a slight performance trade off depending on what kind of skiing you like to do. I keep my edges on my pow skis dull because it’s slightly easier to slash and dash in crud and makes very little difference on icy terrain. For fully cambered directional skis being ridden very aggressively, it would make more of a difference. Every once in a while i’ll do the edges on my firm snow skis though if I’m bored, since a few years ago I bought a full diamond edge tuning kit and feel like I need to get some use out of it.
Point being, I’ve never found sharp edges matter much for most recreational riding. None of this has any relation to being uncool. Maybe in your wifes scenario, having razor sharp edges would have saved her from breaking her arm; almost certainly not.
The comment seemed like a "I don't wear a helmet because it's uncool" sort of thing...just do your edges occasionally, what's the issue?