Your junglers were probably being idiots in a good chunk of these times. However, you have to understand that when jungling, you can't just show up wherever, or you get punished.
If I show my face in a lane to cover, I immediately lose map pressure. A good enemy jungler can take dragon, gank the other lanes, or counter-jungle. Knowing where I am, he can predict where I'm going, ward up, and warn his laners. Or he can farm safely and back to buy.
If I show up in a lane to cover, I am also wasting a lot of time. If it's 7 minutes, dragon is up, bot lane needs a gank, and my red buff is up in 30 seconds, I need to back right now. I need to hit red in time, reach level 6, gank bot, and contest dragon. I really, really can't afford to go mid and kill those 5 minions. The tower will just have to eat it.
That being said, there is no excuse for a jungler who let a tower die because he wanted to kill those baby raptors.