trolling is a form of non-directed harassment.
And here is your problem. You're taking 'trolling' WAY too seriously. The examples you used are what I assume you deem as trolling and if that is what you consider "non-directed harassment" then it is more like a personal issue lol
You know, if trolling were the light-hearted exercise you'd like to portray, I could agree with you. If trolling consisted of a rickroll, or a leekspin (I said LEEKspin, blues), I could look at it and, although tiring, at least see the humor in it.
But really, it's not. It's mean-spirited. Granted, it's not stalking, or outright insulting, but it's done with the intent of causing someone else grief, if only temporarily. A troll is considered "successful" if someone ends up looking like an idiot, moreso if someone else points it out.
Trolling doesn't add anything constructive to the game, and not only that, it's a deliberate attempt at being destructive to the community. Sure, there are worse offenses imaginable, but why should that
be an excuse for allowing it?