Isomorphic Javascript has very little to do with trendy and mainly a function of optimizing for mobile experience e.g. reducing latency, smaller payloads which

Isomorphic Javascript has very little to do with trendy and mainly a function of optimizing for mobile experience e.g. reducing latency, smaller payloads which means SPA and websockets and in real world SPA needs to support SEO, FB scraper etc. so Isomorphic is the only viable real world option.