Re "cosmetic" - I'd agree that the extent syntax matters is more limited compared to semantics, but that limited extent can be a lot of the daily experience with a language! I've ported many bash scripts to Elvish and I still find it liberating to not have to write double quotes everywhere for my script to handle whitespaces correctly.
The biggest innovation here (shells centered on structured data rather than strings) comes from PowerShell. But PowerShell sucks as an interactive shell.
I see the basic concept for Elvish as PowerShell's language power, but with the more Unix-y sensibilities of traditional shells, plus, crucially, the human-friendly focus on rich built-ins for interactivity exemplified by fish.
I don't think a real-world implementation of that kind of idea is a 'merely cosmetic' innovation. There's real novelty in that synthesis. How to balance those inspirations is not obvious, and neither is how to fill the gaps between the big picture ideas and a usable tool.
Go use Elvish for a while and you'll see how much creativity has clearly gone into it. Hell, just browse the GitHub issues and you'll see.
It's not cosmetic in this case. As others have already pointed out, the elvish version handles a few minor but important special cases that bash does not handle.
