What would the ideal features of a web based text adventure interpreter have?

I'm a programmer and I've had a play with a few text adventure tools for my own amusement - and found them to be quite annoying to use, very non user friendly - and illogical trying to appeal to those who can't program with natural language but then trying to make it Turing complete.

So just for fun, I figured I might play with writing my own.

Given an ideal world, what would you want an interpreter to do?

Features I had in mind were.

1. Multi platform, designed to work well on mobile / pc etc.
2. Allow for importing standards that already exist such as blorb, z, ulx, html, quest.
3. Allow for scripting in a c/js style language.
4. Display images / map on the right hand side, text on left.
5. Allow for the creation of multi user dungeons.
6. Have a bunch of user created extensions that are easy to include.

Any thoughts would be appreciated, vapourware this might well eventually be. But there's definitely some modernisation that's very much lacking from this world - sites that exist such as textadventures.co.uk seem to be heading the right way but not quite joining the dots for me.