Well, having been one, I can say you guys are demonstrating half the reason - being used as a punching bag by one side of the aisle, based on half-truths and selective anecdotes. The other half of it is being used as a pawn and hostage by the other side of the aisle.
It's no harder to fire a Federal worker than it is to fire a union member, in fact it's a damn' sight easier compared to firing a lot of union workers. The 'Being paid twice as much' is only a half-truth, there are just as many professions where they drastically underpay for the level of qualification and experience they want and get (Compensated by relative security and a retirement plan that isn't all that, but at least can't go bankrupt). I won't go into a long and boring technical explanation of all the ins and outs on that, but I did Federal labor law cases for twenty years and have a pretty good handle on the whole process.