IMHO, built-in support of api-only application is very good. Here are the reasons I can think of right now: 1. unify people who are looking for a standard appr

IMHO, built-in support of api-only application is very good. Here are the reasons I can think of right now: 1. unify people who are looking for a standard approach to create api in Rails 2. clear separation between lower level http support and higher level html/js/css processing 3. performance improvement against using regular Rails for api 4. easier upgrade for app developers