I've had no experience with anyone I know of committing suicide, but I am not seeing how to evaluate whether it is or isn't socially acceptable.
On the other end of the scale we can talk about "Dying with dignity", "Not being a burden to loved ones", "finally at peace", "being in a better place".
When more people hold the later views then it is more acceptable in society for someone to commit suicide because they don't feel that they are hurting others as much/aren't as evil for doing it (not that I believe they're at all evil I used that wording as those considering suicide may be self loathing).
You could even make arguments on a case by case basis if you wanted from the heroic last stand to a single parent leaving behind their children. It all comes down to what obligations we feel people have to stay alive.