My plants also got ripped this year. They weren't even flowering as well, and I also know who did it. It was this fucking pikey (trailer trash you yanks call these vermin). He was so stupid he probably didn't even know that it's the flowers you smoke, not the leaves! What an idiot.
I can understand why they would do it. They think it's illegal and you're doing something wrong and so stealing it wouldn't make a difference. Plus you wouldn't call the cops on them because you're breaking the law anyway. But really, it's just a plant, not a collection of photographs of little boys being raped or something equally disgusting and wrong. They don't realize you're not doing anything morally wrong and that what they're doing is stealing your hard work. It's really cruel actually, because you tended to that plant with loving care as if it was your own child, and what do they do? They rip it out of the ground opportunistically, destroying all your hard work and effort in one go, selfishly just for a bit of bud.
If I ever caught a ripper I don't think I'd be able to help myself from giving them the hiding of their life. I'd try not to because two wrongs don't make a right, but I can't say I wouldn't if the opportunity arose.
This is why when doing guerilla grows I always chose multiple sites scattered around different areas so if one is found, which is invariably is eventually, then it won't matter since it's only a fraction of the total grow. You can easily set up cheap digital cameras good enough to catch their faces to set off when a trip switch is activated since they'll probably be back looking for more. It's always good having a picture of their face so that if you run into them in your locale you can follow them home and make sure they are too afraid to steal from you again. I don't mean beat them up, but give them a good scare if you can.
Anyway, sorry to hear about that, it's gutting I know. I felt like my dog had died when my Blue Widow and Blue Hash plants were ripped out of the ground about 6 weeks ago, especially since they were the healthiest, bushiest and thriving plants I'd seen in a long while. What goes around comes around though, as they say.