DMX is an amazing protocol, however it seriously suffers in that it's an output only protocol. Depending on your needs, it may or may not work well for you.
DMX controlled lighting can be very inexpensive, but fixtures add up. There's a lot of DIY kits to control LED's and other lighting via DMX, which is pretty cool, too. To add input support to DMX (eg, trigger a light or cue by sensor), you will need something that can do Input into a PC (or controller), and the software to trigger your DMX cue.
The best thing to do is to use the correct technology for the correct application. In our show, we use DMX for our front facade, and occasionally slave a few fixtures together when we don't care what they do, as long as they do something.
If we need to respond to a trigger, we tend to use a microcontroller to listen to the sensor and then drive LED's with it.
Sometimes we don't need to respond to a trigger, but it's super easy to do a micocontroller to create the desired effect... strobes, random flashes, fades, interesting fixture reworks... all LED/Microcontroller driven.
The possibilities are endless, just depends on budget, skill level, and proper use of the available tech!