I don't mind that we move in the direction of Windows for a lot of things (there are good reasons for Windows dominance in the market, and anyway Puppy is for Windows refugees); however I think this is one that should stay "Linux". It is not hard to learn at all and sometimes you want control over what is mounted and what not, without having to physically plug and unplug stuff. After a while you don't want to go back to the windows model.Not automounting is by design. Puppy has one of the easiest mounting systems I've seen. However, I'll mention your suggestion for automounting because I've seen a few posts requesting it for removable media.
Anyway, windows does it half-assed: it auto mounts, but still requires a manual dismount (which I bet a lot of people forget to do on USB devices). Going manual both ways just reinforces the correct behavior.