Sure, you could hack into the tables now if you wanted but your add-on wouldn't really be recognized or certified by AC as they don't have the SDK arrangement. I think many people on this board know how to do the hacking from previous posts but this is in no way supported by AC.
An SDK just would make it official that the add-on programs would be considered before future releases. Also, the relationship between the developers of the add-ons and AC would be made clear by this arrangement.
An SDK should also put into place a more structured release management process for dealing with db structure changes. Makes the programmers think twice before they make changes to the db structures that could screw up a person's addons.
