The walkable townhouses and height-restricted buildings you're talking about (1.) only exist so long as the aesthetic/lifestyle value of a low-risey city balances against the demand for more housing and developers' desire to make money and (2.) make public transport trips take longer because you have to walk past more of your neighbors' low-rise buildings to get to a public transport hub and the bus/train/whatever has to travel farther (past the low-rises) to get anywhere and also make more stops if more hubs/stations have been built to offset the problem of people living relatively far apart in those low-rise buildings.