Believe me, they can be exceptionally dangerous if used correctly. Have you seen what a single space bomb does to a fed cruiser? Like, wow. Yes, they cost 15000cr each, but then missiles cost just over 3000cr, and when you consider how much damage 15000cr worth of missiles do (that's just under 5 missiles, or about 6% damage), then the bombs are good value. I personally don't have major dealings with them, because I don't want to have to trek half way across the galaxy just to reload.
They are better than heavy rockets if used correctly. I find that a good tacticis to run towards the cruiser, turn your ship, launch the bomb as the cruiser comes onto the screen, then leg it away as quickly as possible. It works, and it really dishes out the damage. If I want to take down a cruiser in, say, a corvette, i sell the rocket launcher and buy in the bombs. Kill the patrol ships and then kill the cruiser with the bombs. nice.
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I choose to believe that the glass is half empty.