They've been at it for over 40 years and grew to the most valuable company in the world. In many computer fields they still are THE platform (anything design for example) so clearly the software they do have is plenty.

Can you elaborate what you mean by shooting themselves in the foot?

Do you see them as a centipede who sacrificed one foot in exchange for all the riches in the world?

Or do you mean that if they were more open to developers they'd somehow be even bigger? What's bigger than a trillion dollar company? Would they be intergalactic?