One reason I've heard is the much higher cost (and lower availability) of appropriate lumber. The forests were mostly cut down hundreds of years ago, while in north America, that process is still underway (though thankfully slowing a bit).
I'm not sure forests being cut down is the problem these days. Wood is one of the most renewable and sustainable materials out there. Old growth has been cut down, or become out of most people's price range at this point in NA, but farmed fast growing pine is cheap and sustainable. Perhaps NA has more land to support such farms though.
The US cut down its forests too! Since the early 20th century, it started to replant more trees than it cut, and now has an ever increasing area of forests, much more than in 1930s for example.
Total area is up .. from the 1930s. However, some of the most wooded areas (e.g. the Pacific NW) are currently at about 20% of what they were when europeans arrived.
