You must have different nippers than I do. No problem for me with glued fretboard extensions.

Fret ends at the professional levels of the trade are a bit of a signature thing and there is no "perfect" only different styles as J is pointing out.

Here are some criteria that I look for and again it's a personal thing with no written right or wrong however there are things that clearly are more functional than others, that's what I look for.

1). Preservation of as much of the valuable top of fret real estate as possible without..... being proud or sharp. Or, in other words, no radical bevel like f*ctories do....
2). Intentional!
3). No fangs.....
4). scratchless and refined.
5). This is huge and don't laugh, we see it all of the time especially on Luthier built guitars - NOT loose.....

Fret ends at their best are not noticed.... and not in any way an impediment to playing. Players only seem to notice them when there is a problem so don't create any problems..... Because after all guitars are tools for musicians....

I've never had anyone ask me for a specific style of ends but we have been asked plenty of times if we can nix the stinkin.... radical bevel and preserve valuable fret top surface.