GoKawiilOne clear advantage of passive wired systems is modularity. Because the amplifier and speakers are separate, you can replace or upgrade one without rebuilding the whole setup. That matters when you're putting together a stereo or home theater system you expect to keep for years.
A wired connection also removes Bluetooth transmission from the latency chain. Bluetooth can introduce a delay between the source and the sound reaching the speaker, with the amount varying between devices. Video playback can often compensate by delaying the picture to keep it in sync, but it's harder to mask in video games since the sound needs to react to what you're doing. The Bluetooth Special Interest Group's explanation of LE Audio describes buffering in Bluetooth Classic Audio as one source of that lag and explains how LE Audio can reduce it.
That doesn't mean a cable automatically makes music sound better, though. If the source is a lossy audio file, some information has already been removed during compression. Switching to a wired connection can't put that information back. The quality of the speaker, amplifier and recording still matters, as does the room you're listening in.
Cables are the obvious trade-off. A basic stereo pair is usually easy enough to wire, but setting up surround sound can mean running speaker cables to several points around a room. That can limit placement or leave you figuring out how to hide wires along walls, under rugs or behind furniture.