In D22594#498890, @ngraham wrote:

As for the feature itself, for the past few years I'd been opposed to this, on the basis that people should just use the built-in Baloo-based search instead. But unfortunately the requests keep coming in, and there are use cases that Baloo doesn't work for (e.g. on external disks), so there does seem to be a need, or at least a desire. And we do already have this accessible from the search panel, so this is basically just a shortcut to that. I'll give this patch a fair shake.

"Prohibiting the use of Dolphin as the actual root user (not using sudo or kdesu) breaks legitimate use cases for using the root user. "