The most popular premium (and free) themes almost all have Theme Options, places where you can go in and change the way your WordPress installation work. Sometimes theme options focus mainly on design, such as letting you choose between color schemes or upload a header image. Some themes have much more elaborate options panels where you can choose the home page display, configure slideshows, select categories to feature, and so forth.
As I understand it, theme designers create these added features by building WordPress plugins into their theme designs, either directly into the functions.php file or by bundling the plugins with the theme. Sometimes they use plugins from the plugin repository; sometimes they write the plugins themselves. (Watch out for errors when you try installing these themes through the WordPress dashboard. You’re going to want to unzip them first and upload them with an FTP client.)
Theme options are wonderful for new users, and they can save even experienced users time hunting through and testing plugins. (Is the one I used on the last site still up-to-date? Does it conflict with anything else I want to use on this site?) Also, a good theme designer will consolidate scripts, and that can speed up the site’s function; running too many plugins is not necessarily kind to your server.
The first time a DIY type like me encounters theme options, they’re pretty baffling. For one thing, they can run counter to the way WordPress is designed to work. Woo Themes, for instance, won’t display their own home pages correctly if you have already set WordPress to use a static page as its home page. (This is true for many other magazine-style themes; I just happened to encounter it first with Woo Themes.)
For a really drastic example of something that interferes with the normal actions of WordPress, you can try WP Remix. There are a number of good things about this theme, if you’ve got the design chops to make it look pretty. It comes with templates for enough different page layouts to make your eyes cross. But there are a couple of tricks to using it that will really trip you up if you don’t know them, and the documentation could be a little clearer on the subject.
First, you have to choose the template from the special field that the Remix editor inserts, not from the normal WP page template drop-down.
Then you have to click the “send to editor” button to activate the template. The editor box will fill with filler text and images. You have to replace that carefully so as not to mess up the layout. Naturally you can’t use an offline blog editor the way I am now.
But even when you’re not dealing with such an extreme case, controlling your site through theme options rather than plugins means that as soon as you change themes, all those features are going to go away.
So whatever time you saved in the beginning by using theme options, you might be losing as you scramble to re-create what you had.
And wasn’t part of the point of WordPress to keep things like design, function, and content separate?
Right now, on November 12, 2009, I’m using a theme with functions on this site. More and more themes have them. Maybe all themes will have them soon. But I actually hope they won’t. And I may still switch to a plain-vanilla theme and just install plugins if I want a featured content slider, etc and so on. That way all of those things will continue to exist if I change themes, and WordPress will continue to work the way the Codex says it does.