I saw AN post last night and you guys have beat me to it.
Just looking at the tax question in a straight forward way. Why would anyone want to pay the government $3 to get $1 back? Of course if you have to or want to have a mortgage the write off is a good thing leaving fairness to non-owners out of course..

Mortgage money is pretty cheap still,even so
Putting mortgage money into savings long term is a no go obviously.Putting it into cd’s or opening a heloc and trying to time the market housing for leverage investment is another thing especially if there are other asset available to cover.Some people like the idea, some don’t but it has been successful over and over.The opportunity costs of having disappearing equity tied up in a house in a down cycle are big for average wealth people.This cycle for those holders me included, might end up like winning the lottery and watching it dissappear.Of course we have an advantage going forward because our debt load is low but not because we are making the most sound financial decision. Mortgage money is pretty cheap but most of us are dependent on wages to pay for it. I don’t think an investor needs to make a paid off house a sacred thing, regardless of how comfy it might be and it could be leveraged to good results.

Another thing..If a house is not an investment why have so many of us paid for “homes” with the gains from other “homes” which would never have happened if we made a stupid investment into the first,second, third…one?
Yeah, I know I am preaching to the choir, mostly.