IEMs don’t usually get damaged. The cables can get damaged with usage. So it’s easy to replace them if they are conveniently detachable.
Detachable cables allow you to swap out different kinds of cables. These can feature materials that make a difference to the sound signature or different termination types like 2.5mm or 4.4mm, which are sometimes needed to plug into various devices.
Balanced Cables are upgrade cables that make a significant difference to the sound quality when used with a device featuring a balanced output, usually a 2.5mm or 4.4mm output. Swapping the cables for a Balanced cable allows you to take advantage of the balanced output on your DAC or Player and can improve the bass, soundstage and resolution of your IEM.