1,000 miles-unless you have been offroad a lot- is not much mileage for a chain---unless it was very low spec. in the first place which is a very good possibility on this bike. You caught it well within tolerance so as not to cause any other problems with wear to the cassette or chainrings so no major problems there.

So why change the cassette? You would not notice any difference on performance and it would not improve the Gear selection and there is plenty of life left in that "Low" level SRAM cassette to see you through next season. By then you may decide that you want different ratios on the cassette and that will be the time to change it.