Someone asked about this in 2010. I have also asked and highlighted about this internally but I feel it fell into deaf ears.
I strongly feel this should be addressed by now. GS should re-look the library management. SketchUp and most CAD softwares have a good way of handling components/blocks where users do not have to worry about missing objects. Purging unused and unwanted objects is an important aspect of file management. Archicad may have a better object libraries but I feel the management is still "old school".