They are almost free, they don't augment mass nor volume, they don't bring the need for more crew and mostly, they makes you able to do VERY MATURE THINGS :
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Wait for it
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I'm not ashamed.
But seriously, use them, beyond the blinding bloom they may be useful someday (simulating hangar bay for example)
More seriously you can almost make thin GLOWY ANNOYING bars of them, sector size and basically this is a way of griefing for almost no cost. I feel this is a bit wrong, the block have some uses but this is too easy to abuse them. Maybe limit the volume of those block at no more than 2x the current volume of the ship?