Improving commuter networks invariably helps housing but it does further the trend of allowing (from a planning perspective) the hyper-concentration of industry. These centres inflate local property prices and top-end salaries, forcing lower-end people away from where they work. As new commuter towns get established, the lower classes and forced further and further away.

They've been trying variants on this for two hundred years in the UK. It's always ultimately self defeating. The only way you fix it is dispersing industry.