Crazy Eddie wrote:
... is another good question that deserved an answer in 1979.
In many respects, the 1979 Enterprise was very well designed. I don't recall there being much unused space in the plans and there is at least one thread in Fan Art where people have mapped the interior to get rid of some of the inconsistencies with the original plans. We do also have to remember that Starships need space to carry passengers, equipment, and ships, depending on their mission.
I'm a subscriber to the notion that starships were never designed to land on planets, although saucer sections were designed to do so in an emergency. Voyager could do it but I think she was far smaller and I think that size DOES matter because of the amount of energy required for something that dense to escape a planet's gravity.
The TMP saucer could separate and land in the same way as TNG but without warp power this would be a temporary emergency measure.
I think it was silly to build the ship on Earth and it was silly to land the ship underwater. It was silly to lose warp power, impulse power, emergency batteries and ALL the thrusters in one go.
The writers of this franchise are prone to do things that they think will look cool without really thinking them through, such as wasting an escape pod instead of beaming Kirk to the brig of the outpost so he can meet a monster.