^That's a good point PS
The only thing I found was although I can understand the actor growing up, I would have thought they would have developed him more. I mean he didn't play an amazingly huge role in season one, if I remember there was all this hype about the character and all he really did was lead Buffy to a cave. Given, it was prophisized and such, but I honestly was like 'yeah okay, soooooo?' just didn't seem like a huge thing, I mean another vamp could have just as easily done so. And then he tried to bring back the Master (if it was him, not 100% sure) which again, other vamps could have easily done, and then Spike killed him. To me, it seemed like the writers decided to "switch" villans after season one. Like the annointed one was originally going to be the big bad (maybe beside Angel, or not, depending on if they'd got that far, I don't know) but then, after writing him in season one, they decided to 'exchange' him with Spike. Because I found that you're right; the dusting of the annoited one didn't make much sense after they'd made him such a huge part of a storyline already, and built him up. And to me, it seemed rather abrupt.
I don't know, if I remember they were originally going to kill off/ just get rid of Spike, but decided against it once they realised how popular he was with the fans. So I personally just figured the writer's quickly decided on an alternate storyline and scrapped the other one in whatever way they could. In this case, dump the annointed, and who better to do it than this than their nice shiny new, rebellious, bad boy with an accentish character? After all, his character was so different than those of the other vampires they'd brought on so far, it would make sense that he, of all "people", would dust the great annointed one.
Can't complain though, I never much liked the kid-vamp myself 😉