There's a real emotional difference in clicking on a movie poster rather than squinting at text in a list of folder contents.
Additionally the media server will generally pull lists of actors, directors, and other related works, as well as holding your place in the episode or series if you are working your way through a TV series on the weekend. "What episode where we on?" becomes a rhetorical question rather than a debate.
What is the benefit of this being a server side function?
Sounds like the opposite of a feature. Never judge a book...
(1) Pulls media metadata automatically
(2) Can serve content to a variety of clients, including smart phones
(3) Provides user access controls for when you want to share your content with others
(4) Can transcode media on the fly for clients that don’t natively support a media format
(5) Allows you to logically split up your content into libraries
(6) Provides powerful search capabilities using metadata (e.g., by actor, by genre, by director)
(7) Provides support for audio as well as video content
Handles organization and searching for various media
Additionally, clients available for smartphones and Android TV devices.
And most importantly for some people is being an endpoint for accessing their media remotely