Ditto on that. Doesn't PM bare cover most of the smartphone concerns already?
Before I get into your question I would like to thank you for pointing out that version of PerlMonks, I did not know about that and here are some screenshots on Opera Mobile and Android. After taking a few minutes to try it out on the desktop and cellphone I can now answer this question. The 'bare' mode does make the browsing experience better in certain cases but other tasks are now harder to complete. Let me explain by going through some of the interconnected design considerations for mobile devices (this is also largely applicable to regular websites as well).
Emphasize content over navigation. The bare mode takes this to the extreme by removing everything except the main site content. This does make the content first but it also makes navigation harder. With no menu at the top there is no clear way to navigate to other sections. The only available links are the ones intermixed with the content which are targeted at said content not exploring the site in general. This method is also called the "hide n' cry" method. Just remember: "Mobile users will do anything and everything a desktop user will do, provided itís presented in a usable way."
Pivoting and Exploring a website are common tasks all of us do when using a website. The bare PM has no main navigation visible and no way to access it. The design I am working on compresses the navigation into a drop down select menu that it accessible via a single click. The technique I am using borrows ideas from Convert a Menu to a Dropdown for Small Screens and Unobtrusive Dropdown Page Changer. The goal is not to bury the content in navigation bars but have navigation easily accessible from a central point, usually at the top of the page. Here are some mobile screenshots of a select option and a toggle menu:
Align with how people use their mobile devices and why. The book "Mobile First" does a great job explaining this:
Maintain clarity and focus. This idea ties back into "how people use their mobile devices". If you look at the mobile usage reports like this report from 2010 you see that 84% of users use their smartphones at home and who really focuses all their attention on doing something on the phone while at home? Looking into the other times cell phones get browsing use it is easy to draw the conclusion that the end user's full attention is not focused on the web page being consumed. This leads to a browsing habit known as "one eyeball and one thumb" which means the design needs to take into account external distractions. Removing excess navigation options from pages and removing visual clutter are the two main vectors for solving this problem.
The bare version addresses some of these problems but how it is accomplished degrades other browsing tasks. This is why we still need a better mobile experience since the mobile market is growing and projected to grow even faster.