You do have a valid point, you don't so much replay the whole game as you simply skip over to the fork in the road and choose differently but you're still playing the game again even if only partially
Since visual novels having more than one route has become sort of a "expected" thing and it already counts as replay value, I'd consider extra if it has unlockeable routes or perhaps hidden extras and so on. In this day and age where games and visual novels along with basically every other medium gets more expensive it's important for them to be replayable but shouldn't really be forced, I've always considered that it was important for the consumer to feel like he got his money's worth of content.
I can't stand Clannad, Kanon, Air and to a lesser extent little busters either their anime or visual novel counterpart but it's because of a personal preference when it comes to art styles, it creeps me out