Therein lies the whole issue. You want the iPad and macbook to converge ala what Microsoft has done with the Surface Pro, a product which, for all the praise leaped on it by the tech blogging community, hasn't exactly caught on with the masses, because it causes as many problems as it solves.
You are taking the needs and desires of what is likely an extremely niche but vocal group of users and attempting to project them onto the entire iPad community, without also considering if that is what the rest need or want, much less if such a move might be deleterious to the overall user experience.
And they shouldn't need to. The iPad is a touchscreen tablet first and foremost. Developers should continue to optimise their apps based on the assumption that users will interact with the app via the touchscreen and only the touchscreen. Everything else is of secondary importance.
Because a mouse would change the interaction between literally every other element in the OS. The mouse pointer has a presence even when there is no active input, which is exactly the opposite of the touch model—input only exists when the user is pressing on the screen, and when they let go, that’s it. The mouse pointer has a position on the screen and continues to exist even when its not displayed or being moved. You can ‘hover’ a mouse pointer over something.
So how do you handle the mouse in the touch system? Do you treat it exactly like the finger? So your click is exactly like your touch? Launching apps is then a single-click, and drawing requires that you click and drag all around the screen? What happens when you reach the end of the screen? Fingers stop touching the screen, but the mouse pointer is now jammed up against the side. You can lift your finger and randomly access anywhere on the screen quickly, but with a mouse pointer, you’re confined to linear motion—you cannot simply go from here to there without crossing the intervening space. THEN you have the additional trouble of making the targets on the screen sufficiently accessible to a mouse.
The user interface guidelines would be a mess. Menu access would suddenly become necessary. You’d have to consider Fitts’ law all over again.
If Apple were going to do all that work, there’d be no reason to duplicate it, which is why I say that mouse support won’t happen unless they merge the OSes into one. It’s a considerable amount of overhead for very little gain on their parts. From your perspective, it seems like you should just be able to move a mouse around and click, but from theirs (and by extension, the perspective of the app developers that would be on the hook for handling this interaction model), it means re-inspecting all sorts of assumptions that they’ve left as solved.
The ASK remains an optional accessory for the iPad. People are not forced to use it like they are pretty much forced to use a keyboard and trackpad with a Macbook. You are free to detach the iPad and use it as a tablet when it would be more conducive, or dock it and type away for when a dedicated keyboard is more suitable.
It's up to you to decide which compromise you would rather make.