I fully agree with you couch is very powerful and it really does reward creativity, you can do a lot with the admin panel especially using the message type editable, but moving forward the admin panel does need to change because natively its not very friendly and for the couch users who create new sites constantly, having to also create a better admin panel for a basic website that has a lot of templates is time consuming, but possible.
The message editable allows us to do all sorts of things, like you said. The landing page idea is one of the lesser important things from this post, because it can easily be achieved (very easily, I might add) but the general layout and navigation of the panel and the way templates are managed and grouped is what really needs improvement.
While we can alter the view of the panel through the tag with JS and css overrides, its still a "hacky" solution, and requires manual editing and messing with with each change, sometimes that just isn't worth the hassle when you handle multiple couch managed sites. There's workarounds to most of the current issues if you're creative enough, but we're hoping to get some of the "workarounds" to have more permanent solutions natively, which improves couch for the average user and also makes it slightly easier on developers, when they don't have to worry so much about the admin back-end but rather can focus fully on the front-end.
On-page editing is actually very useful, but it has its fallbacks. For example, as far as I'm aware and have tested - it's not possible to use on-page editing for gallery pages (whether inline OR pop-up editing). Again, we can probably create solutions for this via DBF but we couch will be improved overall if we fix some of these things in the default panel.
Lets make an example, because it will probably illustrate easier than my words can today lol
We have the awesome dynamic sitemap template that KK created a while back, this template lets us worry less about our sitemap files, we can have them updated automatically when a client adds a new cloned-page for their blog post etc. However, this template is a work-around only. I say this because there's much you cannot do with it, but also there's much that needs to be manually done with it on a per-site basis. For example - all list-view URLs must be manually added to the template on each site, because it cannot output different views (as far as I've been able to configure it). Also, if we wish to hide specific templates or pages, we must create large if statements manually defining each template to be excluded.
So while we can currently achieve all of this within the template with some manual editing and a little time, its more complex than it could be (and after all, couch is aimed at being simple) which it is, though experienced developers who can write php etc have a much better time I'm sure. Ultimately like all products similar to this, addons and "hacky" ways of doing things that improve usability of the product and make it 'better' are often worked into the product as full solutions (often with developer twists and differences, but you get what I mean)
so I guess I do agree we can do most things within the confines of couch, and the message editable is indeed a strong hidden feature that allows us to do a lot of this, the point of the post is more of a look at what the next version of couch should have feature-wise that we currently have to go without or create more complex and advanced solutions to achieve, which doesn't suit the average developer that couch's audience targets.