As it happens, tabbing around a badly designed form often doesn't work correctly. Then there are UI with hundreds of focusable inputs where while tabbing might work correctly, is extremely cumbersome and slow to use.

This is not to suggest replacing a keyboard with a touchscreen, any more than suggest a keyboard is no longer required since a mouse or trackpad is available. It's just an additional form of input, and one I'd personally definitely miss.

I agree with you. The keyboard/mouse has been a standard input combination for PCs since the 80s. Maybe it's time we added touch to the standard. Seems some additional input methods are likely well past due.