It would make the blend with the corridor service more appealing since both the Surfliner and Cascades offers it but CS does not and where a sleeper is overkill for short distances.
That's a great point. I use the CS between Salinas and LA, and this would be a very attractive option. The CS can and should be doing double duty as a corridor train -- it runs nearly the length of the Capitol Corridor too (all except the one train to/from Auburn). To bring it up to the same level as the corridor trains, though, it needs to handle roll on bikes, at all the stations.