First Genesis Rock can be reflected by Ex Mode in Jp version too, that is nothing new. Quite easy too, I can do it consistently against max level AI.
And Flare being reflectable IS a big deal. As a good deal of characters have a boost in their priority, Mateus now have more people who can reflect his Flare out right.
Genesis Rock is also easier to dodge, it does not home in on the target when the rocks fly out (They fire off in set directions now, IOWs), and the raising rocks come out much slower. Golbez also moves slower during the move as well; its considerably less powerful than it was in the Japanese Version.
No, Flare being reflectable is NOT as big a deal as you're making it out to be, NOW THAT HE HAS AERIAL FLARE.
Just cause you CAN reflect it doesn't mean the person will get that chance. Look at how Emperor Fights; he's constantly applying pressure. The way Flare works is that it sneaks in on the guy while they're busy dodging the death field he makes. There are only a few characters whose reflecting attacks mock this (Terra's Tornado is an example, but...Terra crushes Mateus without worrying about Flare anyway; his issue is that he just doesn't do well against ranged opponents, given they don't rely on mobility as much; you know, this is to be expected of someone who rides on taking advantage of the terrain.)
Furthermore, the big isssue with Emperor was NOT that Flare was reflectable; it was that it was his ONLY GO TO HP ATTACK, and it was GROUND ONLY. He couldn't do shit in the air; he had to hope the person lands and then hit them. However, now with Aerial Flare? Suddenly he can fire off a move that reflects OTHER Projectiles, sneak in on a close range attack, the Aerial Flare serves an extra mine that while the person is busy avoiding the ground flare, accidentally lands into it...I could go on.
You really underestimate how much Emperor's Aerial Flare improves him. It sounds like "Oh, just one more move, yawn" but in reallity, it compliments his fighting style so well, its not even funny. FURTHERMORE, the Aerial Flare can't be reflected; it gets nulled out...which is hardly an issue, cause he can just fire another one on the spot, and its like nothing bad happens, and the reflecting attack will likely subside by then. Again, only a few characters can realistically pull off these blocking based moves without danger of being hit by something.
Also, Niu, congrats; you're the first person to hype Cyclone Slash. It is generally considered a bad HP Attack with so many god damn flaws, and one of the easiest things to avoid. Its also among one of the most predictable moves ever, and its not even that good on priority either. The move has a lot of issues, so no, don't go "I do not have to explain the brokeness." The only thing its good at is tripping up the AI...which only really worked in the Japanese version, as the US AI avoids it consistently now. In the end, its just a Tornado/Genesis Rock wannabe. So it can shut down Chaos' Attacks! ...um, most characters can dodge right away from it, and nail the character with a ranged attack; its actually pretty awful at shutting those down.
Cross Slash also has issues; while Cloud is reflecting Ground Flare...Emperor gets a free Thunder Crest on him. Braver is a different story, but again, you can't just go "This move works, therefor, its a good option!" In the case of Cross Slash, that's a PERFECT BAIT opportunity for Emperor, Flare comes in on Cloud from a distance while he's on the ground, he tries to reflect...oh look, Thunder Crest or Sticky Bomb to the face, now Emperor gets a free shot.
Again, you're looking at things way too simplistically. "Flare is still reflectable" actually has applications now that Emperor can USE TO HIS ADVANTAGE, such as baiting. True, he's completely boned against someone like Terra who can stay away from him, and still reflect Tornado, but that's what we call "Counter Picking." Most characters cannot in fact apply these reflectable moves as reliably as you want against someone who actually can use Emperor.
Oh yeah, another application of Aerial Flare?
People use to be able to dash through his mines, so if Emperor was in Air, he had nothing! Now, if they dash to him...Flare to the face! Again, don't underestimate how much a "Go To" HP Attack in the Air helps him.