It's a distinction between entertainment and sporting.

Sure, if you just want to enjoy some diversion, don't waste your time on something you don't enjoy. A work of literature or artful film may be worth a bit of work in order to appreciate the beauty and to learn from it, but that's something more than entertainment or gaming.

If you are looking to develop some aptitude, skill, or ability through a game, you're doing something other than simply seeking entertainment. In Go, you need to learn to give up on structures that are doomed. But you don't just forfeit a game as soon as you start losing. If you are going to improve as a player of Go, you must play your hardest to the end, attempting to achieve the best you can, and perhaps even snatch victory from the jaws of defeat. Same goes for pretty much any game where skill or ability come into play (athletics and strategy games being the primary examples).

Quitting at the first sign of trouble only encourages low frustration-tolerance.

1 & 2: Defenseless planets bugs me too. Why not just have some cheap satellites with phasers and photon banks? Or maybe it's part of a armament de-escalation treaty?

3: It was a tiny black-hole. :-P

4: If I remember right, the Narada and the Enterprise warped away after the drilling stopped. They might have been light years from Earth.

5: Some sort of back-story involves the Narada being extra-advanced and incorporating Borg tech and the ability to reconfigure and repair itself. They also had two decades to get fixed up.

6: No clue...