Joomla, by comparison, got the menu right (but little else).Your post made me curious. Could you post a screenshot on why a menu in Joomla is more optimized for 50 or more pages?
Well, there are two major differences:
1. In WordPress, you can have a menu that shows all categories or all pages. (Categories are used to organize blog posts, while the page menu links to static pages. Both categories and pages can be nested). You can have either of the two menus on top, and both on the sidebar. The menus are generated automatically, however, so no matter what theme you use, you don't really have much control over the structure of the menu. You can only hide certain categories or certain pages. Also, the menus you choose will always be displayed the same way, on all pages. (There may be plugins that give more control over WordPress menus, I don't know yet.)
In Joomla, by contrast, you create menus manually, which takes some work. But this means you can have any number of different menus and show different menus on different pages. (There is a little hitch to that, but in general that's what you get.) You can have two or more items, in different menus, that link to the same page, for example. You can create menu items that link to individual pages, or items that link to blog-like listings of articles, or items that link to "table of content" layouts with links to more stuff. And certain plugins add their own menu types - e.g. there's a photo gallery plugin that adds a menu item type that automatically creates a gallery page. Maintaining the menu(-s) does take some work, and if you change the menu item that links to an article, the URL of the article will change too, which is bad. But overall, Joomla's structure is much more flexible, especially if your site is not all a blog.
2. The second difference is in the way the menus work. Here's a menu of static pages for my blog site (in Polish), using a free WordPress theme called Fusion:For those who write articles on CMS, a question.
It's quite long already, and imagine what's going to happen when there are three or four times as many pages. It's not easy to find stuff in it, and it's not easy to navigate. The selected page is not highlighted, and the nesting, while indicated, isn't all that clear (nested items should be indented). And it's still the best effect I can get - all other themes I've tried were worse in this regard. To improve, the menu should be collapsible, indented, and should only show the expanded portion.
This is the same WordPress menu, displayed on top:For those who write articles on CMS, a question.
This is better, because the menu is collapsible, so the lists are not as long. But (a) this menu can only be shown on top and is only navigable with the mouse, and (b) if there are many levels of nesting, it will not be very usable, either - much like the Start menu in Windows. And since you can only have one menu on top (the "better" one), you have to choose whether to use it for pages or for categories. The other menu has to live in the sidebar.
I do not have the same menu composed in Joomla, so the effect of comparison will not be as persuasive, perhaps, but this is a typical Joomla menu on the sidebar (using a commercial theme):For those who write articles on CMS, a question.
It's pretty small, but you can see that only the "path" to the current page is expanded: New products -> eStopWatch -> Download. Graphical indicators make it easy to see where you are in the overall menu structure. If I now clicked the "Activehotkeys" item, the currently expanded part of the menu would fold, and the clicked item would open up. Perhaps such a menu is also possible in WordPress, but I haven't seen one like that.
Now, here is the same Joomla menu displayed as a top menu:For those who write articles on CMS, a question.
This one works pretty much like the top menu in WordPress, only here it's prettier. It's the sidebar menus that really differ in functionality.