LookML have the benefits you list, and I would rather author dashboards via LookML. And, I need to use them, because I'm usually prototyping a dashboard that will then be modified programmatically, and then this is pushed out into multiple projects.
However, as well as the confusion for end users that you mention, I think it's worth considering whether you'll be let down by the content management and discovery of LookML dashboards. I would argue that content management and discovery of LookML dashboards is so bad in Looker that you would be well advised to stay away from them if you can. After all, getting the content you develop used in your organisation and useful for other people is probably the point of doing it.
Here are my thoughts on why you would not use them.
The main discovery issues:
* LookML dashboards are listed separately from all the other content in Looker, i.e. undiscoverable through Spaces.
* LookML dashboards are presented via their own separate page, and on this page the Looker user is presented with an unfiltered list sorted alphabetically regardless of what Model they belong to. In my case this list is 1000 rows long.
* In the Search Results, LookML dashboards are not listed in the Dashboards section. Instead they are in the 3rd set of search results like some kind of outcasts.
Other discovery issues:
* LookML dashboards do not appear in the Top Content list.
* Lookml dashboards cannot be made as Favorites.
* LookML dashboards do not show up as Recently Viewed content.
* The dropdown navigation box (top left) on a LookML dashboards links the user to every single other LookML dashboard. In my case I get a dropdown list of 1000 links.
* LookML Dashboards are named like something that only people with developer mode should be seeing it. Most end users of Looker will never edit (or know of) LookML so why use such an esoteric name as their label? Personally, I would label them Curated Dashboards. (Well actually I'd just rather label them Dashboards and have them with the rest of the Looker content.)
Plus, they’re missing from Usage reporting, so you can’t really tell is they’re used or not. You'll have to know what Explores are being used within them and work back from that.
Regarding the LookML dashboard roadmap:
I was told in 2014 that better organisation of LookML dashboards was coming, but actually since then the organisation of them has gotten worse - the long LookML Dashboard list used to be filterable.
So while I'm sure better support for LookML dashboards is on a roadmap I’m guessing it’s a fairly low priority and not something one should rely upon.