Tornado still too low level.

    - It's verbose compared to flask.
    - It reinvent the wheel, while flask uses great components such as werkzeug.
    - If you want to make a component, it's complex.
    - It doesn't come battery included for the Web like Django, just the bare minimum.
    - It misses the opportunity to provide task queues, RPC or PUB/SUB which are key components to any modern stacks are made easily possible by having persistent connections.
    - It ignores async/await potential of unifying threads/process/asyncio and don't allow easy multi-cpu.

Don't get me wrong, I think tornado is a great piece of software, but it's not match against innovative projects we see in Go or NodeJS such as Meteor.