While lovely, that's obviously not true. Houses are places to live, but someone has to own that house - either you, or some sort of investor (or govt), and since not everyone can buy a house (in any country in the world) there has to be investors for everyone to be housed.Houses are places to live in, not investments to achieve capital growth.
As to what house prices are reasonable, it totally depends on the economy, which is ever changing. With interest rates as low as they are, house prices are really too cheap today, but obviously we expect interest rates to rise at some point, so with that in mind I think house prices are a little (5%) high at the moment.