Treat your users like children, and they'll keep acting like children
I forgot that most distros now install the cpu hog known as tracker by default, so sure enough, it started indexing my files while I was doing other stuff. Of course, I killed it, then removed it, but still, this got me to thinking ... why do we need desktop search?
The answer, of course, is that we don't take two minutes to teach someone the easiest rule for organizing stuff, whether it's files on your computer or anything else.
The Rule of Most Specific
People tend to go with the defaults. So, when creating a project called Foo, they will stick their code in Projects/Foo folder, but the documents for that project end up in a Documents/Foo folder, their backups in a Backups/Foo or Archives/Foo folder, their graphics resources in a Pictures/Foo folder, etc.
The Rule of Most Specific says that instead, since all these things are related to a specific project, they should ALL go in Projects/Foo. So, documents related to Foo go in /Projects/Foo/Doc, backups in Projects/Foo/Bak, graphics in Projects/Foo/Img, and any files being served locally from the users public_html directory should be in Projects/Foo/public_html, with a symlink to /home/$USR/public_html/Foo
Of course, since designers think users are total idiots who are incapable of learning a few simple rules, they think it's much better to index everything ("let the computer do it for the user") and then force the user to wade through a bunch of search results to find the one thing they're looking for.
The end result is that people aren't given an incentive to organize things a bit, and as a result, their backups are incomplete ("gee, who would have thought that people don't want to go through a dozen different directories all over the place to assemble a backup for a specific project"), and they waste time looking for stuff because their drives are a mess.
In other words, it's the same as in real life when you were a kid - you learned the hard way that it was quicker to put things where they belong the first time than to find them after entropy takes over and you can find everything except what you're looking for. Or your place looks like an episode of "Hoarders."
"Oh, but now I can search for stuff on my drive by tag!!!" So what - now you have the extra work of figuring out a tagging scheme. It's easy to remember "The graphic I used as one of the wallpapers in project Foo" and look in Projects/Foo/Imgs/Wallpapers, or when you need to transfer a copy of all the files so you can work on another machine, just tarball the whole Foo directory and know you got everything.
Use the Rule of Most Specific to put stuff in the most specific place the first time and you'll find things quicker with just a file browser than you could using any desktop search application. Or prove the "designers" right and keep treating your file system like a kids messy room or the junk drawer in the kitchen.