Let's agree to disagree. "Traditional computing" is a slowly declining market. There are now far more non-traditional computing devices out there than traditional PCs. Why would Apple limit its horizons by turning iPad into a PC input device?
iPad is a dandy, business-class input device. However, the backend is not on PC, it's in the cloud - large scale corporate databases/database-driven apps that would swamp any desktop computer.
The world of PC-centric computing long ago reached its practical limits. Any desk worker that had use for one has had one for decades. Meanwhile, the growth of mobile devices continues in the workplace, as all those workers who are not desk-bound can now easily connect to business systems without walking halfway across a warehouse, restaurant, or retail store to interact with a desktop-bound PC/terminal.
iPad may not be what you need in a business computing device, but that doesn't mean your personal needs are sufficient to drive an entire market.