Toasters are nice things to have, but they are trivial. I like to make toast. It's nice, even fun sometimes. But I write at my computer. I do a lot of my thinking and creating here.
Simplicity implies that everyone has the same needs.
In toast, that's more or less true. In computers it's not true. Computers are used for lots of things. You can create special-purpose computers by limiting options and making them less general. Maybe, if you do that very well, they are as useful as toasters.