Why?
The only wrong I can attribute to suicide is not considering the effect of your death on other people, and by this I mean things like signing a contract in which you promise to do something, but then can't because you killed yourself.
The emotional suffering that you might cause others is something else to consider, by they don't have the right to cause you to suffer by preventing your suicide. If you have your sense and you want to die, go ahead.
Now if you were talking about how disruptive it is to just commit suicide out of nowhere, I can agree with that. If you're going to kill yourself, you should do things like have credit cards canceled, and also notify the police (probably have them watch it too under controlled circumstances so that no one could fake the call and then use it as a cover for murder). Basically, euthanasia for the healthy.
Calling it cowardly is ridiculous though.