Well I kinda agree with pol. It's a method that game developers use to reward the curious players or make the lazy ones re-play the game. Though I never ever re-play a game to finish some special side quests because I find it very boring. So I think there should be a balance, Of course you should not punish a player because they want to follow the main story only, You should not disappoint them just because they don't want to explore more. On the other side, You should make sure adventurous players will be rewarded too. That's why I have only a few of these missable items and quest in my game, To make sure both curious and lazy players are satisfied lol
I don't really like the idea...When the boss is defeated, He's defeated! It doesn't make sense to fight again...
of course, I think everyone agrees on this
lol it reminds me of a sentence I read in a level design book. It was something like, "Players are not your enemies!" and sometimes I really need to remind myself that it's right