We would love to bring improvements earlier and some things will likely appear in interim (service) updates, but every major feature update requires testing, packaging and a lot of community kicking. Also many web-masters could use longer periods between worrying about updates.

Look, about a month is needed for the after-update fuss to calm down and first service update to appear. Then, we would need anywhere between 2-3 months to plan, design, develop and fine-tune new features. A month for see more betas/RCs at least. Anything less than 6 months would have to be rushed, with a lot of compromises.