The consumer likes the ability to customise and personalise stuff. This has always been the case. Remember the Nokia 5110? It had a changable cover and snake! It probably set the ball rolling all those years ago into making a phone an accessory and lifestyle product rather than just a phone.
The apps can offer new features that make the device easier to use or add new features. The customisable features that'd be nice too for a lot of things.
Now, I think the idea of an app store for a toaster is a little silly but having an app store for your cars entertainment system, TV etc is great.