The iPads have missed expectation. The expectation was PC is doomed because of iPad. Now after four years iPads sold less than 200 million units. Compare this to several billions of PCs. The iPads are still a fraction of PCs.
Productivity software usually needs more ram and storage to run. I think one of the most important and widely used productivity software is MS Office. I also think the reason MS has not ported Office to iPad is 16GB iPad not capable.
This is one of the biggest mistakes Apple made in positioning iPad. iPads have much bigger screen than iPhones. They are more suitable for productivity. With productivity one generally needs more memory. Apple is steering many productivity users away from iPads.