Why not? It's a decent way to ascertain how powerful a device is. (Although maybe not Linpack -- it doesn't really correlate to real world performance, in my experience. Vellamo or Quadrant would be better, but they don't have iOS equivalents, IIRC.)

In case you have been living inside a barrel for the last few years, there's an all-out performance war in the mobile system-on-chip space going on at the moment. Phone and tablet manufacturers pretty much expect everyone to be pushing out a new chip every 6 months and there's a huge fight over who gets the most design wins the next generation.

The fight is not only about !/$, it's more and more about !/W these days.

Benchmarks are also relevant to customers who like games or other heavier stuff on their tablets. Then there's a bunch of low-end Android tablets that are simply too slow to be used for anything. So the high-perf tablets and phones want to distinguish themselves from that.