The whole idea behind chromogenic B&W film is convenience. It's been around for a long time now, but it seems to have taken on a new life with the emergence of digital imaging. By that I mean, you shoot the roll, drop it off at the drugstore, pick it up in an hour. What you get are not quality prints. They are proof prints. But if the drugstore is using a digital or hybrid system, and you can get the pictures already scanned on a CD, that represents a tremendous convenience over getting the conventional B&W developed (either yourself or a service, and it usually takes more than an hour - more like days), then getting or making contact sheets or proof prints, and then scanning. Scanning is tedious, time consuming work. Now, if you're going to be making enlargements the traditional way, and you're not interested in the CD for web display purposes, then the convenience factor of C41 B&W sort of evaporates.
However, that being said, there can be technical reasons for still using films like XP2. The first is the incredible exposure latitude as already mentioned, compared to conventional B&W. This can be extremely useful in "toy" cameras that have no exposure controls, for instance, or in vintage cameras without a meter, or if you have to shoot in various levels of light all on the same roll. The second reason is, as already mentioned before, the actual picture quality. With XP2 and equivalents, you can get a certain smoothness in the picture that can make 35mm look like medium format. I know I may get some argument about that, but it's really that good, when used in the most optimum way possible.
It may not be the traditionalist's choice for B&W, but it's definitely worth trying and experimenting with.