A little late, but I have three aspects of this to offer.

1.  When we are little, we like new things better than old.
A shiny toy over a dull one.  (Other things being equal.
I'm not suggesting that we discard our dear old teddy bear
the first time we're offered another.)  A little later,
it becomes generational.  My generation wanted clean simple modern,
not fussy old Victorian.  Do some of you remember "The Postwar
World" of the early 1940s, with highways ramping through the sky
and helicopters buzzing the super-skyscrapers?  In college
I read an article about a proposal to put a dome over downtown
Fort Worth -- I guess this was before air-conditioning --
the idea being climate control.  I told my girl about this,
with enthusiasm, but she replied slyly, Gosh, then they'd
never have to breathe fresh air again, would they?  That may have
been the beginning for me.  Still later, I went from thinking
why would I want an old copy of a book if I can get a new copy,
to seeking out old books.  And finally I came to prefer most
old buildings to most new buildings.  For me it was an evolution
of preferences.

2.  Rich women read Architectural Digest and stuff like that.
How I turned my California Ranch into a Cape Cod for only $5000.
If they have money they look for ways to spend it, and preservation
isn't very visible (ideally it's invisible!), and it doesn't
express *their* ideas, compared to "re-do"-ing the place.
Hence the gut rehab of a Louis Sullivan house in Lincoln Park.
The rich are the worst, not because their taste is better or worse,
but because they have the means of destruction.
(And women are usually the ones most interested in the house)

3.  Preservation requires a wide variety of skills and so the
run-of-the-mill contractor can't or doesn't want to learn it.
You have a tile roof on your brick house, and a few tiles are
broken?  Louie the roofer comes out.  He only does roll roofing.
His business is booming because his roofs are the cheapest
(in terms of what it costs right now).  He says,  They don't
make tile roofs any more.  Let me give you a nice modern roof.
(Why should he advise you to search the metro area for someone
who does tiles?  and the tile repair will cost more, this year,
than Louie's entire new roof)

This is all from first-hand experience, either as a neighborhood
activist, or as a preservation advocate.

The biggest threat in Chicago now is teardowns and new developments
in historic districts, ugly infill.  It's the males' turn to
spend money destroying (most developers being males).
Turns out it's cheap and easy to tear the old house down and build 6
condos, and the neighbors hate it, but you make big money quick.
And you can use the same design in every neighborhood.

I could go on and on.  (obviously)

Martin C. Tangora, Vice President
Landmarks Preservation Council of Illinois