Re: custom fields: This makes little to no sense to be in core, because custom fields are just that, "custom". There's no point in giving the end user the ability to make their own meta boxes hooked to custom post meta if there is no plugin or theme actually using that meta data. Creating a meta box is something that the theme/plugin should do, because it's actually going to use the data gained from that meta box.

In other words, the horse goes in front of the cart, not the other way 'round.