I'm frugal. Well, ok, I'm cheap. I'm a DIYer and I won't pay $40 or more for a light switch. I believe the more complex you make something, the more you add places for it to go bad or wrong. I also know that the power line is a harsh place electronically, so unless something is built like a tank (read very expen$ive), it is likely to fail sooner or later. So ease of and cost of replacement is a major factor. And now that I'm using more CFLs that cannot be dimmed, I'm going to more of a lighting-by-design approach and instead of dimming a light, I use different or multiple lights to get various lighting levels (scenes), but I don't use many of those, either.
I have no X-10 in closets. ;-) I use them for a few things here now. Smallish house (well, 2000 sq ft on 2 floors but some of that is under low hip walls), rural setting (but I am on my own transformer), and a separate garage. Oh, and a chicken coop. I use X-10 for a driveway street light, porch lights, chick coop lights and heat lamp, area light, bedroom and living room lamps, and motions sensors for most of those. I even have an X-10 controled light in the crawl space to check the oil tank level via a remote camera.
I also use X-10 for the odd item like small fans and little appliances. I have them on my de-icer wires on the roof overhangs to keep the ice dams from forming as a temporary measure this winter, and they are working fine there. Holiday lights are naturally X-10, too. The HA system also has temp sensors and weather stuff, but we're getting away from X-10 there. I also have X-10 RF remotes all tied to my HA system.
I used to have a lot more stuff - cameras and ninja bases and such - and while I still have a lot of that gear, I'm not using it here yet. I still have some noise issues with X-10, but for the most part it works prety well here. As someone mentioned above, don't use them where you have critical needs. I have more reliable methods for those really critical items, but most of that is not automated through the HA system at my home.