Not heavier bullets per se, but bullets with greater sectional density tend to penetrate deeper. "Heavy for Caliber" bullets tend to have the greatest sectional density for that caliber. I think there are limits to that though, the standard pressure 150gr 9mm bullets don't outperform the standard pressure 147gr bullets.
The story of the 380 is a great case study in how not to design something. Usually you start with an issue or a problem that you're trying to address, that generates requirements that must be met, and the requirements dictate a solution. I know that the cartridge was designed around 1907 and that is part of my point. Colt wanted a new cartridge that could be used in the Colt 1903 with a minimum of modification and that is exactly what they got. Anything else that the .380 ACP does is incidental.
If bullet manufacturers today set out with specific objectives and requirements to create a cartridge that produces somewhere around 290 ft-lb of muzzle energy out of a 3" barrel (this is toward the high-end of 380 +P) with an emphasis on penetration, I'm sure they could make a round that can be fired in the smaller locked breech pocket pistols that has better terminal ballistics than the 380 ACP.
Boy, I have started any number of long winded answers to your post, C0untZer0. I think the problem is I don't really want to criticize your ideas, because they are interesting and well thought out.
Yet I find that idea that 380 ACP is the result of of a flawed design process jarring, to say the least. It is one of the most popular automatic pistol cartridges in the world, and has been for a century, give or take. It has easily outlived potential replacments like 9mm Makarov and 9mm Police. If you think the process that led to a thing that so many people have found so useful for so long was flawed, then I think maybe you need to re-evaluate.
Similarly, the better cartridge you describe really is better, no question. It is also so similar to 9mm Parabellum that I am afraid I don't see the point. Once again, maybe I am missing something.
Finally, I would point out that there is a cartridge that pretty much meets your design specs for a 380 ACP replacement. It is 9mm Browning Long (9x20mm SR), which has the heavier bullet and higher velocity you desire, without getting into 9mm Parabellum territory. Nobody has wanted to design pistols for it since about 1930, and I don't think getting rid of the semi-rim and shortening it up by 2 or 3mm is going to help. Maybe it would be useful with today's designs and materials, but that ship has sailed.
You know, somebody in the revolver forum had an idea for a modernized 38 Short Colt cartridge that sounded a lot like your modernized 380 ACP. Most people there had a hard time with that idea, too. I think you are trying to hit too small of a target between 380 ACP and 9mm Parabellum for other people to see the appeal.
I understand the feeling, because I am actually a big 9mm Browning Long fan and lately have been seeing the .442 Webley as a good cartridge abandoned too soon. And if talking about 442 Webley here isn't thread drift, I don't know what is.