Though it's been over a decade since FRED2 was released, it's remained a robust and effective tool for designing quality missions. Especially with all the additions that the SCP team has piled on over the years, we've been able to do things with FRED that
would never have thought possible.
FRED's versatility is a major strength. I'm a quest writer for a Unity-based free MMO, and I'm constantly hamstrung when thinking up quests by how little functionality I have to work with. FRED, on the other hand, gives you the tools to pull off all sorts of tricks with events, variables, and SEXPs to get whatever effect you're trying to create for your mission, and that's not even getting into scripting.
So: why else is FRED awesome, what cool stuff have you been able to do with FRED, what cool stuff do you think FRED can do that you've never got around to doing, etc.?