Belling arrived in Milwaukee in 1989. He knows nothing--nothing--about Brookfield. But that doesn't stop him from telling us all about it.
He states that Brookfield turned purple because Brookfield Square and lots of offices developed, bringing scads of people along who now live in that city.
Actually, Brookfield's rapid residential development began in the early 1960's, not after 1967 when Brookfield Square opened. The commercial development of Bluemound Road was fairly slow; Trammel Crow's major office park wasn't opened until the late '70's, e.g. By about 1985 there was little room left for residential development, proven largely by the fact that post-1990 development rests in largely lowland/swamp areas.
As to whether it's purple out there: yes. Why? Maybe it is the retail and offices. But if you want to look at more serious causes, blame the too-easy flow of money and the college "education" stuffed into the heads of many residents, entirely different from the hardscrabble lives of pre-1960 residents.
Material comfort tends to go hand-in-hand with a lack of yeomanlike self-denial, which is the core of virtuous development in man. That was reinforced by the Left-Lurch of colleges which began in the early 1960's and was in full swing before 1970, even in "Catholic" schools.