Even though most WBB users have variable experience with coding and might be able to create custom pages manually (like suggested here), I believe that a wide majority isn't able or doesn't have the time to do so, as in my case. This is why I really wish there was an addon that would allow to create custom pages within the ACP, and that would include an editor (plain, PHP, HTML, etc.). There was such a plugin available for WBB 3.1.x that worked quite well, but unfortunately it was never updated for WBB 4.x
I am aware that there is a free plugin, in fact called Custom Page by mobahner, that allows to create custom pages. However, the author never updated it, and its language variables for English were never included, leaving a bit of a mess in ACP. I started fixing them manually one by one and re-packing the file, but some of them wouldn't stick, with the result visible in the screenshot below.
I think that having a decent custom page plugin is long overdue, and I am willing to pay for its development for a reasonable price. Also, I am sure that such plugin would become rather popular in wbb-store.
I hope that some willing developer will decide to go ahead and make an addon that I'm sure most, at some point or another, many will find it useful.