if everything else was equal
But it just isn't. That's like saying a solar powered car would be better than a gas powered car assuming the sky were always clear and you actually live in Seattle.
Velocities are different and recoil is different. The velocity helps make up the difference in size and the less recoil makes it easier for the average shooter to connect with the target on follow up shots. As has been repeated over and over again, shot placement is king. If you don't hit a vital area that puts the attacker out of the fight what good is it? Now does that mean the 40SW is useless? Far from it as there are people that shoot it well. But as my local gunsmith tells people about caliber, "a hit with a .22 is better than a miss with a 45".