The only martyrs people talk about are those who died for noble causes, furthering civilization and equality by our modern definitions.

Well, in my field I would disagree with that assumption.

One of the key developments in modern Islamist terrorism was recontextualizing "suicide bombing" into "martyrdom operations". It's my understanding that this was first done by Hezbollah but really took off with Hamas and some of the other Palestinian organizations. It's also become a trope (the precise history I'm not as familiar with) to refer to all Arabic war casualties (on your side) as martyrs. So as an example, an Emirati newspaper won't say "Three Emiratis killed in Yemen" it will say "Three Emiratis martyred in Yemen."

So sure, we can use "martyr" in a positive sense, but it's a politically loaded word and one man's martyr might well be another man's terrorist.