Maybe because we have just so many desirable tree choices?

My experience with the local retail nursery industry would indicate quite a few are sold and planted here but are all pretty small to start with. And are not an overly noticeable tree until they flower and turn that fall fire engine red. There used to be a large, established specimen in the Pinehurst area of north Seattle but haven't passed that way in in few years to know if still there.

They are also a Great Plants Pick.

I had a young one at my previous home (SW Portland) and it was around 5' tall when planted. It was very slow growing and didn't fill out well, but I think its location didn't have the greatest soil. Even though it was small it still had gorgeous blooms and bright color each year.

I knew I wanted one after seeing an older specimen at a friend's house. It was probably 30+ yrs old.

I love sourwood... the flowers are lovely and the fall color is spectacular. A homeowner in my city has one planted in their front garden on a main residential street. In the fall, they have a realtor-style document holder out by it with info sheets on the tree. That's how many people were stopping to ask about the sourwood!

As others have pointed out, they are VERY slow growing. If you are patient, they are a worthwhile tree. I have mine planted in a mixed border with other trees nearby (ginkgo, snake bark maple) so it's not a problem that it is taking it's time getting bigger.

Thanks everyone. This answers my question.