Hollowpoint loads are generally not going to expand, unless they hit a fluid medium. Thus, when they hit intermediate barriers, they're going to behave like FMJ.
If someone's concerned about shooting through intermediate barriers, such as automobile glass, dry wall, etc., and still get reasonable expansion, there are plenty of choices on the market that will allow one to do so, such as Speer's excellent Gold Dot, along with many of the "bonded" hollowpoints.
On another note, FMJ isn't a bad manstopper, even in the 9 mm Parabellum. The NYPD used FMJ in their weapons all the way up to the 90's, and didn't really have complaints about its manstopping performance.
Where I will not argue, though, is that FMJ has a greater chance of overpenetration.