Question: When Commander Morrow responds to Kirk's protests he says "Jim, the Enterprise is twenty years old. We feel her day's over." In ST: TMP, Decker said "This is an almost totally new Enterprise." If the Enterprise was, for all intents and purposes, totally rebuilt from the original, with more space, better engines, etc., how could it be twenty years old?
Chosen answer: The Enterprise may have been extensively refurbished, but that does not mean it is entirely new. The ship is still 20 years old. Also, that was Decker's comment, and it may have been an over-exaggeration. Newer ships were being designed and built in the meantime, so even if the Enterprise was still mechanically sound, the technology may have advanced so much that it was not possible or it wasn't economically feasible to continually retrofit older vessels.
Chosen answer: Scotty spent the best years of his career as the chief engineer of the flagship of the Federation: the Enterprise. His time has passed, however and the Federation is rumored to be planning on the Excelsior becoming the new flagship. It is a larger ship with a new, experimental warp drive. Scotty hates the Excelsior primarily due to his pride in the Enterprise but also because he is unimpressed by the design of the Excelsior. The trans-warp drive is easily sabotaged.
Chosen answer: Kruge only had the proposal video that talked about what Genesis was. He didn't have any actual data on how Genesis works or how it could be created. Having footage of a nuclear blast doesn't give you knowledge about how to build a nuclear device.