I guess you forgot something important: P-skills mostly scale from weapons too, therefore finding a good weapon can give you a bigger boost than mages will ever get.
Also physical was always more of damage focused, while magic was more about applying effect, which will get totally denied as long armor is left.
Another aspect in the first game was magic featured a lot of ways to make damage go out of control. Chaining explosions, forcing enemies to walk on fire, and a bunch of other crazyness. Often making enemies who were immune to such cheapness suddenly shook the difficulty level because you couldn't just make a wall of fire to kill all the enemies.
Though yeah the spells as a whole didn't do anywhere close to the amount of raw damage that Physical did in the first game by a sizable margin outside elemental chains. You could expect your warriors to get double damage on you.
You also got some great buffs and amazing debuffs. While Rogues had as much CC as Mages did, mages also recovered spells faster.
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Now the issue with the leap to this game comes almost entirely from three key changes
1) Area Denial has been severely weakened: Fire Floors don't immediately win you battles (nor do they immediately kill your friends)
2) Movement Ability has been boosted (Enemies don't waste a billion turns trying to get up to you)
3) CC almost never kicks in unless the armor is gone.
You can see the effects rather prominently.
Firefly was a great skill in DOS1 because the ability to paint fire really controlled the battle field. Yet in DOS2 it would be not very useful (better than Fireblood) and thus it isn't in the game. Fire had to up its game and create HUGE pockets of flame creating almost unmanageable amounts of fire.
As well because enemies can run like their butts are on fire it means mages don't get much in terms of grace before they have to start firing into your own lines making spell casting very surgical.
CC has been severely handicapped and there are very few forms of CC that even penetrate armor (Slow, fire, and poisoned) and the forms of CC combinations usually don't work until after armor is gone making them useless (No point in doing Chill + Water).
As well because of the armor split it means that the first armor destroyed is best. Sure enemies can have a lot of armor and low magic defense, but even now that typically just means that if you had an extra physical member that you could take them down just as fast.
Yet there is more
1) Physical fighters are even more CC Heavy than before
2) Physical Fighters still have a lot of damage over mages.
Mages typically only show their magical might with Earth + Fire... Right now the Air + Water combo ability is weak.
