As a Roblox user, it’s currently too hard to find players by their previous usernames. This is because in the majority of cases, the player with the previous username is shown last in the search results and this can result in the end-user having to navigate through multiple pages of results in order to find the profile they were looking for.
This feature would be beneficial to Roblox and its users as it would provide more accurate search results (because no one else has the exact search as their previous or current username) and would make the process of finding someone by their previous username much easier.