Trimming the comp to the work area does not set out points for your layers you just can't see them because the viewable area in the timeline matches the work area. If in doubt go to the composition settings and add a little time and you'll see that they still extend beyond the work area. If you just want to render or preview the work area then set your preview to work area or set your render options to work area in the Render Cue or in the Adobe Media Encoder.
no it really does cut them.
I'm using CC2014
If you extend your layers then Trim, it will also trim the layer
What are you trying to accomplish? You can't see anything past the end of a comp, so having a layer extend beyond the end of a comp doesn't seem useful.
I have an expression tied to the layer that moves it in and out based on the inPoint and OutPoint
I don't want the layer to move out, hence extending the layer past the cop area's end point