The purpose of that is to allow WP themes to run the bp directories such as member, groups and blogs. It has nothing to do with the member theme at all.
What the themes are for:
https://codex.buddypress.org/getting-started/using-the-buddypress-themes/
Well, personally I consider the member and blog directories to belong to the same “type” of page as the profile and other pages that use the member theme.
But, more to the point, the problem I’m having is that plugin-template.php relies heavily on proprietary BuddyPress functions which makes it hard to integrate into themes with layouts that are different than the basic BuddyPress layout. Since the member theme is designed specifically for BuddyPress I figured it would be easier to have the pages that use the plugin-template.php use that theme rather than writing code that changes the way the blog themes display just for that one page.
I mean, it should be possible to have the “members” and “blogs” directories use the members theme rather than the main theme since “members/username” uses the member theme. I was hoping that there would be an easy way to do it (like bp_get_member_header() or something like that). Oh well.
Nope. Sorry. The directories all have their own css you can skin. bp has a site-wide.css file you can drop into your theme in /themes/<your theme>/css/site-wide.css
In bp-core-cssjs.php which fires up the css and js for bp is this fn:
function bp_core_add_css() {
// Enable a sitewide CSS file that will apply styles to both the home blog theme
// and the member theme.
if ( file_exists( WP_CONTENT_DIR . ‘/themes/’ . get_blog_option( 1, ‘stylesheet’ ) . ‘/css/site-wide.css’ ) )
wp_enqueue_style( ‘site-wide-styles’, WP_CONTENT_URL . ‘/themes/’ . get_blog_option( 1, ‘stylesheet’ ) . ‘/css/site-wide.css’ );
wp_print_styles();
}
add_action( ‘wp_head’, ‘bp_core_add_css’ );
Unfortunately, that doesn’t actually make a big difference in my case; the main problem I have is that the header and footer files between the two themes are vastly different. The two main problems are that 1) one of my themes is fixed width at a size smaller than the minimum size for the BuddyPress themes (which breaks the layout) and 2) they don’t have the header with “Home”, “Blog”, etc. which I don’t want on my main site, but *do* want on the members directory and blogs directory.
I was thinking about it, though; the member-theme actually has plugin-template.php although it doesn’t appear to be used. Is there some particular reason why if a blog theme doesn’t have that file it puts up an error message instead of redirecting to the member-theme file?
The member theme is not a standard WP theme it can’t be used as such. It puts up the error message because it’s required. 
I’m not sure why the member directory and blog directory have to be handled as part of the standard WP theme instead of the members theme?
You are asking in a support forum why design decisions were made and why, considering the evolutionary nature of software, bp ended up as it did. As an end user of bp I have absolutely no idea how to answer either of those questions.
The real answer is that things don’t have to be like they are if you don’t want them to be. Come up with an enhancement and share it with us. That’s the beauty of open source under a GPL license.
Code is Freedom.
Ah, I was trying to ask if there is there something about the code that makes it impossible to implement the redirect I was talking about. I am definitely interested trying to code an enhancement, but I’m new to BP (just installed it a few nights ago) and, while I’ve coded a few WP plugins for personal use, there’s a lot about coding plugins/hacks/etc that I don’t yet know.
In other words, I’m trying to figure out 1) if coding a redirect (or other function) is within my current coding capabilities, and 2) if so, where to start.
Sorry for being such a newb 
The plugin-template.php file does exist in the member theme. I don’t know of anyone who has tried such a thing. The member theme has a header and footer file. Andy keeps telling me that any WP theme can be converted to a member theme. There may be some guidelines that you might find useful in the /wp-content/member-themes/member-themes-readme.txt.
Andy keeps insisting that it’s not a big problem. I keep saying ‘uh huh’ and ignoring him. Andy is usually right.
tekanji, sorry if my response to you was kinda abrupt. I get ‘tech support cranky’ some times. Ask me ‘how’ and I might be able to help. Ask me ‘why’ and I get defensive even though I didn’t write this software.
Andy keeps telling me that any WP theme can be converted to a member theme.
It can. The member theme is like a normal WP theme but with added functionality. Because of the nature of the themes I run on my site, I decided to customize the member theme rather than trying to convert my WP theme into a member theme, but the principle is the same.
I’m going to check out the the bp_styles() function mentioned in the readme.txt. It seems like as good a place to start as any. Thanks for the tip
Andy keeps insisting that it’s not a big problem.
That what’s not a big problem?
No problem; I should have been more clear with my question anyway. I don’t have all that much experience with open source, but I can certainly understand being defensive about software that you’re very involved in.
For the record, this is the first time I’ve actually participated in development forums for any software I’ve developed for. Most of the time I just lurk and hope my questions get asked by someone else. It speaks very highly of BP that installing it spurred me to actually make an account here and start posting questions and whatnot.
BP is about inspiring community interactions, so it looks like it’s doing its jorb.
