so basically you're saying you haven't seen many if any good junglers, so naturally it must be a bad choice... not true
just because people cant do it right does NOT mean its useless, or a bad idea.
i can't fly a plane but you don't see me saying flying or being a pilot is a bad idea. same concept in a nutshell.
look at the bigger picture, many games have succeeded with a jungler, BECAUSE of the jungler at that. while i understand you're point of view, the conclusion you are drawing from it is just incorrect. i'm sorry you haven't seen positive results from a jungler, but that really just comes from lack of seeing it done right, which is really horrible luck on your part, nothing else
also, after reading some of it again, it seems your experiences are more from people failing at solo top, which is slightly different than just having a bad jungler. sure they're put into a 1v2, but there are many champs / players that can solo 2 people easily, its just done differently than 1v1 or 2v2, and i'm guessing thats where the person playing that 1v2 spot fails. if you see someone in a 1v2 lane and they're trying to farm it anywhere near the mid point between towers, or even trying to push it... they're going to fail 100%, it just won't work.
i stand by my original statement of it just being REALLY bad luck on your part being paired with so many teammates that either fail jungling, or failing solo top vs 2 opponents. i still say that has nothing to do with the setup and more to do with one of those 2 players failing, or even both at the same time. i've seen it happen, but i've also seen one person hold off or even win their lane vs 2 people, so i know it works beyond just "theory"
that last point tho is something i feel a lot of people confuse when getting upset at having a jungler or saying its pointless, i wonder how many of the games they base that opinion off of, the jungler was actually doing well but it was the solo top that screwed it up, and they just blame it on the jungler forcing a 1v2 lane, and disregarding how the jungle player even did.