I would love to see a search and re-link function that searched all folders at tthe click of a button, just like Premiere. Is there any reason this has not been applied?
The rationale has always been performance considerations due to a) how AE handles footage and b) how files can be scattershot all over the place since AE doesn't have a dedicated media management nor require a specific external asset file structure. Relinking stuff could take forever if some tiny image file has been pulled from a deeply buried folder, especially if folders don't match. On the other hand the assumption for Premiere has always been that people use specific drives for their video and those are designated in the media manager/ preferences, so searching would be more straightforward. Personally I've never been a friend of auto-relinking and such as I simply consider it a sloppy way of working with poorly organized projects and files and ultimately even if such a function existed it wouldn't necessarily save your bacon...
Copy the name of the missing Source Footage item in the After Effects Project tab and then paste that into the search field after choosing File > Replace Footage > File...
Files on indexed volumes should load very quickly.
If you start with the top most file in the list, After Effects should find any other missing footage items in the same file path.