FYI, Django/Flask would be the better Python analog; Flask is more similar to Sinatra in its structure (not just syntax), and it was in fact modeled after Sinat

FYI, Django/Flask would be the better Python analog; Flask is more similar to Sinatra in its structure (not just syntax), and it was in fact modeled after Sinatra. But as for your main point, I agree - I don't see the appeal of writing an entire application in Javascript. You pick the best tools for the job, rather than picking one and shoehorning it into every use case. Server-side and client-side needs are different, so I don't see any problem in using a different language on each side. To preempt the responses of 'But it's so much easier to use one common language for an entire stack', I'll have to say that, at least for me, passing data between client and server feels no easier (syntactically or conceptually) in Node.js than in Python/Ruby. YMMV.