Meh, not defending Apple in any way but RPM isn't a very useful metric without other specs on the drive.

Battery life and durability are better on 5400 drives. Performance is a tricky one too. Depending on use case, say a PC doing lots of large sequential data (Media)? 10/15k with high IOP and random access times don't actually help much when streaming home movies instead of serving up highly concurrent database records.

This is Apple doing Apple; very well-designed but midrange hardware with a premium price tag.