While Dragon does many of the same things as the JTAGICE, compared to the latter, Dragon is a toy. Bare board, easy to kill, gets confused regularly. Sure if you have the time and inclination to mess with such, feel free. The JTAGICE may appear expensive to those who have more time in their hands and less reuirements for results, but the price difference does not amount to that many hours of troubleshooting the toy.
All in all, the JTAGICE is quite reasonably priced for professional use, not excluding serious hobbyists.
The JTAGICE, same as 5V devices, is not going anywhere in a hurry, whatever your personal opinion may be.