The historical data seems to indicate that you might be able to expect about a 1% appreciation in real value per year (compared to about 6-7% for stocks), but even so, how much of that is consumption of a depreciating house that constantly needs maintenance, and how much of that is investment in the real estate upon which the house is constructed?
I agree with this, it's a difficult comparison to make. You can never really separate the consumption aspect. Even if you buy a house and keep it vacant, you still have to cut the grass, do roof repairs, paint, etc to keep it in mint condition. And you have to pay property taxes an insurance.
But I think that just makes it even less of an attractive investment. You don't have to do any of this with stocks or bonds.