They are great tools. A Magnum shooter explains some of the benefits:
http://www.robgalbraith.com/bins/multi_page.asp?cid=7-6468-7844
As for "worth".....well, that is such a loaded word.
My next major (and first "new") camera purchase is likely one or maybe a pair of G10s. It suits what I shoot a lot of now. For many things I don't need sharpness, quickness, a huge file, etc. In fact, I rarely will need to even print the pix. The silence, size, weight, low light ability, unobtrusiveness, different viewing methods, etc. are great reasons to use these cameras. Their benefits are actually quite in line with many of the benefits of an old Barnack-style rangefinder. Given what the G10 could give me that an SLR cannot, I think they are "worth" the price.
Besides all that, they have manual controls and can talk to the 580. It has FE lock, FEC, etc.
The weird thing is that it seems most folks with some disposable income think the fact that these cameras are so small and so inexpensive means that their purchase makes him or her inferior in the world of conspicuous consumption, and go for a consumer SLR instead. Many (most?) of the folks who are buying Rebels, X0Ds, and even 5Ds really don't need an SLR 90% of the time, and would probably take better pictures with a point and shoot. So, the question to me is not really why are great point and shoots so much, but, rather, why are low-end SLRs so close in price to high end point and shoots? Exactly for this reason. To bait yuppies into buying a more impressive camera when they don't need it. A camera that could lead to a lifetime of buying accessories, new bodies, lenses, etc.
So, I don't think a "real" photographer is stupid for paying a lot of money for a great point and shoot, but I do think that those conspicuous consumers who jump to a low end SLR when they don't need it are probably biting off more than is necessary and not only wasting their money, but digging a money pit for the future.