Hi,
The main advantage to using a micro controller is that you can do
so much with only *one* ic chip. You can build some quite
sophisticated circuits using only one single ic chip, where you could
use as many as 100 or more ic chips to do the same thing without
a micro controller.
Also, as the micro controller chips are getting faster and with more built in
functions and peripherals the applications for these guys are increasing
too so they are being used in more and more equipment.
If you are looking to build some interesting circuits then use any kind
of technology you want, but if you are looking to build some VERY
interesting circuits then you definitely want to look into micro controllers.
Startup costs can be as low as 40 dollars US for a programmer.