I don't know if silence is pointless, exactly, but it's certainly...
...unsound.
You're asking if the spell is pointless as a ritual, right?
Since you can cast it as a ritual from 120 back from the actual area you need to be sneaking around in, you can set up a guaranteed silent area, where the party members won't need to be sneaky to be sneaky. For example, cast Silence as a ritual onto a wall, then blow up the wall to make a new entrance. Nobody is going to hear that because it's in the silent area.
I don't think the Area of Effect of the Silence spell is stopped by physical objects anyways. I think it would already extend to the other side of the wall.