In general I agree, I think most people complaining about the new player UI is overdramatic and geared more toward those who are returning rather than new, and are looking for some kind of quick UI setup for getting into bosses, where you'd need to set up a bunch of action bars to be visible and a bunch of visible hud windows that a a real new player doesn't need. That said though:
I'd also love to explore simplifying things like the ribbon
The ribbon I think is the worst part of the default UI. The rest is decent enough, especially now that stuff like a second action bar and action bar binding is set up automatically on new accounts so it swaps bar for each style. However, the ribbon by default is a mix of "management window" buttons (clicking them opens the large center windows with tabs) and "action window" buttons (clicking them directly opens a hud window).
Personally, I think it'd make more sense to just put all the "management window" buttons on the ribbon by default, and none of the "action window" buttons, even though it might be slightly more effort for a new player to remember which hud buttons are under which management window dropdowns.
The problem I see is that a lot of new players can't tell the difference between the management and action window buttons on the ribbon, so they have no idea whether clicking any of the ribbon buttons will open a management or a hud window, so standardizing the default ribbon to only have the management window buttons by default would make it a lot more clear to new players that clicking any button on the ribbon directly will open a management window, and clicking any of the dropdown/hover buttons will open a hud window. However, I know that conflicts with mobile's ui design/tutorial, and conflicts with the first-order access that's sort of needed for tutorial island's unlocking of one button at a time, but it would probably end up less confusing long term for new players if all the buttons on the ribbon did the same thing by default.