I'm really getting tired of everyone saying that magus is the best character in either of the Chrono games.
I'm really getting tired of how out of every 5 CT fanfics I read, at least 3 center around him.
Am I really the only one who isn't freaking obsessed with Magus? I mean, come on! Sure, he's cool and all, and he's Schala's little brother, but in the end he's just BORING. He has very little Personal Development, and he always acts all stuck up, like he's better than everyone else.
AND HIS HAIR IS PURPLE >:U
Not sure if the conversation has deviated at this point, but I'll address the original question.
I think there are many reasons Magus comes off as "so cool."
For one, he's built up from near the start of the game to be a momentus figure. Most of the bosses in the game you're introduced to moments before fighting them, but Magus gets at least a quarter of the game devoted to fighting him. not to mention his dungeon, which is still one of the coolest in video game history, and his three henchmen, who have enough personality to cure cancer.
Then you get to him only to discover a massive plot twist, so he gets that attributed to him as well. Which brings me to point number two... plot twists. Magus is surrounded by them. His role as the prophet, his role as Schala's brother and the Queen's son...
He's also the most single minded character in the entire game. His entire will is bent on revenge, and he doesn't deviate from that course for any reason (except to occasionally turn someone into a frog). He has no loyalties beyond those that will help him reach and defeat Lavos. Even defeating him, which leads him to offer advice on how to get Crono back, seems to be a selfish act: after himself, he figures Crono has the best chance of defeating Lavos. Along with this, I have to disagree that he's not developed. In fact, aside from Frog, he's given the most back history of all the characters. We get to see his dark relationship with his mother, his attachment to his sister... hell, we literally WITNESS his backstory.
Then, too, his future is left uncertain. Even Radical Dreamers doesn't really finish him, and he's only there in spirit in Chross. Of course, this is true of most of the Trigger characters, but it still adds to his appeal. That he's searching for Schala only makes him cooler, because we all love Schala (well, at least until she stopped dying her hair).
He's also rather innovative in a lot of ways. He was the "cool evil tall guy with long hair" long before there was a Vincent or a Sephiroth or an anime explosion in America. He's also one of the few villains in video game history which you can get on your party.
Lastly, his music rocks.