Is the development of our cities designed for loneliness?
No, cities arise due to an awareness of the benefits of being close to others, people and places that can offer you shelter, security, entertainment, employment, skills that you do not personally have, and so on. The density of settlement, jobs, social spaces, libraries, and restaurants is far greater in a city than in a comparable area of open countryside, so journey distances are reduced and that makes walking, cycling or public transport provision more comfortable and viable. This benefit needs to be safeguarded by social and political structures that defend land uses that do not necessarily generate maximum wealth to site owners, otherwise a city might become dominated by places only accessible to adults and wealthier individuals. That is why "gentrification" is widely seen as an unwelcome trend in any urban locality.