I am not a spokesman for islam (or any religion) and neither are you. At the time islam was introduced to the people in Arabia, it must have appealed to the peoples there. Prior to this introduction, the people must have been even more barbaric, and hence its way appealed to the people. By today's standards, some Islamic pratices may come across as barbaric (eg. the way/method of animal slaughter), but it definitely is a cleaner and more efficient way than those employed prior to its adoption/introduction.
You blame/accuse me of being responsible for blokes joining IS? I take that as a compliment! Oy, I have never touched foot on the Middle-East, how on Earth then would people go join military jihads in that land while I am here, drinking beer and eating char-kwey teow? Please lah, talk some sense can or not?
If you wish to understand why people join IS and/or other jihadist movements, it is a way more complicated and complex issue, you'd have to consider the formation and expansion of Israel, the Palestinian case, American Oil policy, the fall of the Ottoman Empire, the Crusades and a host of other indirect issues, each one biting a little onto the Holy Islam history. For closer issues here in South-East Asia, much of it has to be attributed to politicians playing the religious/racial card for their own gains by stirring the emotions of otherwise simple kampong/rural folk who through no fault of their, happen to be caught in the swirl of capitalist modernisation.
As for how Islam is being conducted today, not everyone muslim follows it. But any changes to it has to come from the Muslim community. You and I, all we can do is stand by the sidelines, and keep our noses out of it. It is none of our business (besides having and sometimes voicing our opinions).
Cheers!