Why do dryers Vent outside?

As winter has now well and truly set in down here in Melbourne I've been having more trouble getting clothes dried at home. The days are too short and my backyard too shaded for clothes to dry in a day on the clothes line and leaving them for multiple days doesn't work much better either. The current cobbled together solution is to hang the clothes on a drying rack and have it sitting in the house for a few days. But, the only way that the clothes actually dry in less than a week is if that rack is in front of the living room heater.

And so it would seem that they experiment to save a bit of cash by not going out and buying a clothes dryer (and getting it mounted etc) may be coming to an end. But it occurs to me that there is one rather silly point about how our house (and pretty much everyone I've seen) is designed. There is an exhaust fan in our laundry and the only reason it is there is to vent to dryer exhaust out of the laundry and out of the house. If the laundry was on an external wall of the house there could even be a direct vent to the outside to get the hot air from the dryer to freedom.

The thing is though, that in summer we don't need a dryer. Even on rainy days using the clothes horse inside the house gets stuff dry pretty quick. So really the only time that we really need a dryer is in the middle of winter, which also happens to be the only time that we need heating in the house.

So why would we pump the heat from the dryer outside and then turn the heater on at home?

What we really need is a good way to divert the excess heat from the dryer into the house.

Of course there is one big issue with this Humidity! You might have to dehumidify the air a bit before pumping it into the house to prevent condensation and the like. But in general a little bit more humidity in the air could be a good thing because of the drying effects of winter.

I hate to see so much energy being wasted and think that we can save a hell of a lot by combining lots of simple ideas into our everyday lives, a little bit here and there adds up to a lot.