In much modern Western popular music, authenticity is a huge component: we expect musicians to write and perform their own music and to have the lyrics be honest and at least somewhat autobiographical.

This makes listeners feel they have a connection to who the musician actually is.

Actors, by the very core of their occupation, don't have that level of immediate authenticity.

Even if you aren't that authentic, if you fit a persona well enough, a cult ensues. Witness Samuel L. Jackson as badass, etc.

Just a guess: most musicians write their own lyrics which gives much more insight into who they are. Actors are always wearing masks.

Plus, while films and television can be affecting and emotionally moving, you typically sit down, watch them for an hour or five, and move on. Music permeates our daily lives and by its nature can get tied up in all sorts of complex emotions and memories.

There are movies that have affected me profoundly but I'd have to watch them again in the right circumstances and mood to even hope to be similarly affected a second or third time. But there are songs and albums that I'd argue will always get an emotional reaction from me barring some weird scenario where I had to listen to them on repeat for days until they were worn out.

Well, consider Merlyn Monroe, James Dean, Audrey Hepburn and co.