Tablets aren't worthless, but they are niche. The niche is where a phone doesn't have a big enough screen, but a laptop is too cumbersome.

1. Video and map display for a drone in the field

2. Reading, you could use a dedicated device, but I don't

3. Secondary display to watch video(TV) passively while working on a laptop, while not around a TV

4. Some games for the bigger display, and increased battery life

One of the things has held tablets back is that historically you had to have a second data plan to get your tablet online anywhere. So most people would get the wifi only models. I find the combination of a phone as the mifi like device, and the tablet as the great combination at times.

You can now share data between devices on some plans, but carrier compatibility definitely complicates things.