Maybe it's easy to forget if your church is not often producing martyrs these days at the hands of Muslims? I could see how if you're in the West in a jurisdiction which is full of converts like the Antiochians or OCA, you could have a lot of these "be nice; Muslims are our friends" types. Their experiences are all in America or Western Europe (so, quite unlike the native or recently-arrived immigrant Syrian), and if they traveled to Egypt or Palestine or wherever, it was as some type of tourist, so they wouldn't have gotten the same treatment as the native Christians even if they were outwardly Christian (since Muslims expect every westerner to be a Christian by default).
But I imagine that as a result of more recent history (the Nord-Ost attack, Beslan, the problems in Kosovo and Bosnia, etc.), the Russians and the Serbs aren't so able or willing to look at Islam and violence from its practitioners in such a remote and detached way as others. When it's still happening to you today, you can't dismiss it as 'Islamophobic' propaganda or whatever; it's just what's actually happening. That's probably why this story touched a nerve with so many Western people: For the first time in modern history, the Western church is now producing its own martyrs on its own soil (cf. the other modern RC martyrs at the hands of Muslims -- people like seven monks of the Atlas Abbey of Tibhirine in Algeria in 1996, or Sr. Leonella Sgorbati, the nun who was murdered in Somalia in 2006; these were foreigners/westerners living in Muslim-dominated lands, whereas this priest was a French man living on French soil where the Islamists are the foreigners).
Probably as ISIS and other groups and individuals ramp up their Islamic jihad against the rest of the world for the terrible crime of existing, more and more of this will happen, and maybe eventually the whole of Eastern and the largest part of Western Christianity will be more like the Russians and Serbs (and Copts, and Syriacs, and the Ethiopians, etc.; which is to say, the people who actually live through this stuff regularly), and less like new-agey hippies in the comments section of a Huffington Post article.