Do we even know if down b is a command grab? Might just be a hit grab, we haven't seen it winning against shields I don't think.
Laser looks REALLY commital. Fast characters will tear Kaz a new one if he attempts this.
Reflect is tied to a motion move which basically means if you want to use it as a reflector you need to predict the opponents move rather than react to it.
UpB's usefulness as a reversal depends on how fast it is. If it has a slow startup all the killpower in the world is not gonna help it. No freefall is nice though.
Shieldbreaking moves are kind of hit or miss...like you don't actually see Sephiroth breaking too many shields despite also having a shieldbreaker. Gonna make for some nice online cheese, though.
Heavy weight is nice but not super important. It certainly ain't saving Ganon.
Tough guy seems to be weaker than Bowser's which already has kind of niche uses. So dunno if this will be much of a big deal.
Invincible moves are nice but how commital are they going to be? If they are too risky they won't be very good. Impossible to say atm.
Spikes are just a standard Smash thing. Most characters have that.
Rage doesn't seem too crazy of a comeback mechanic. 10% more damage is not too crazy.
Like, not saying Kazuya can't be strong but there's really too little info to say one way or the other. The Smash Ultimate team has been pretty good with balance overall so I don't think Kazuya will turn out any different.
--Lazer seems laggier than I thought, but it seems like a nice tool for a shoto character to have who normally doesn't have the ability to apply safe off-stage pressure.
--Reflect requires some setup and anticipation, but for a character who might have trouble getting in, it's a nice tool to have to avoid getting outright camped. Also, even though it's situational, just having a reflector on a random tilt move is a luxury to have.
--His up B seems to be about frame 11 or 12, which is good enough, but made even better because he can act out of it. I imagine it'll act like Corrin's Up B but with kill power, but hopefully it won't be as tough to punish as G&W's Up B.
--True, shield break moves are pretty hit or miss. Especially Sephiroth's which doesn't break consistently unless he has one wing. Ken's shield break is pretty effective though and Kazuya's down-forward tilt seems very similar. I figure at least one of his two shield break moves will be effective, but we'll see tomorrow
--Spikes are standard, but not many have a way to apply pressure on ledge hangers in the form of a spike -- none of the Shotos can apply pressure while their opponent is ledge hanging.
--Ganon is hindered by his poor recovery and slow run speed, which Kazuya seems to not be plagued by. Kazuya's full hop is booty, but his double jump looks floaty and gets nice height, along with his Up B which can be used with mixups. He also seems faster and has a fantastic approach option with crouch dashes.
--Yeah, I guess rage isn't too crazy for a character whose damage output is already insane (what is 1.1x gonna really do). But I was more so looking at that it gives him a move that turns his armored command grab into a move that deals 40% and kills early.
A lot of these attributes might not be impressive on their own, but they're jamming this character's toolbox full of great moves that seemingly don't need additional properties/boosts. As you said, the team has been pretty good with balancing, but some of the recent DLC characters have been pretty nutty (i.e. Steve, Minmin, and even Sephiroth). It's fun to theorize, but yeah, we'll see tomorrow.
Also a couple of things: it looks like Kazuya's side taunt does 23%. And the 10 hit combo, which Sakurai didn't land all 10 hits of -- did 24%. With how long it lasts, shit will probably carry you to the ledge and kill lol.