I think most of the bugs are worked out and we have a fairly "universal" system There are differences, however which may lead you to one over another. The best way to choose is decide how YOU want to operate and how much equipment you will be using. Cost alone should not be the only factor as a poor choice in the beginning may fail to meet your needs and cost you more in the long run.
As far as why - I think the best answer is fun! I like to operate and the joy of seamless operation is worth it to me along with benefits like sound, wireless operation etc. Not that you can't get some of that with conventional DC but DCC gives it to you all in one package.
