That would change the internet, and the world.
- very soon, you wont need to install anything to use IPFS. it will "just work" with js on today's browsers.
- for best perf, yes, we need browser implementations. and... those have begun :)
Do you have links to browser implementations?
On sites not known to me, I typically block most (read all) .js at first, just to make sure that these sites do not leak too much information about me to external tracking tools, advertisers or the like.
So using .js seems to me a bit problematic in regards of people not enabling it by default (but this is an absolut minority, if I look at the stats of the sites I analyze).
It works very well for me so I'd recommend it to others, if they're not already aware of it.
I doubt they're building it in JS for giggles.
In order to make changes like this stick my guess would be that you need to reach a tipping point before interest fades, and to do that you need to take away the browser vendors ability to say 'no' or 'maybe later'.
As you point out, people who don't run JS by default represent a tiny percentage of traffic, so would have to be a secondary concern to be supported later.