A thought to consider. Judo and boxing have weight classes for a reason.
Out in the real world, you probably don't have to worry much about smaller, weaker people attacking you (unless they have weapons, which is a whole other issue). It's the big guys you need to worry about, and that means that you're always going to be at a disadvantage in terms of physical power. Training can offset that, but only up to a point. Sugar Ray Leonard is never going to be able to go toe-to-toe with Muhammad Ali.
So maybe asking about how to get better at hitting is the wrong question. Maybe a more profitable inquiry would be to figure out why so many aikidoka -- some of them very senior and very well respected outside the art -- view hitting as unnecessary. Start from the assumption that they *aren't* all clueless bozos, and see where that takes you.
I agree with your observation on who's likely to attack you, but I'm not sure I agree with your conclusion. There are weight classes in judo and boxing because size is a significant
advantage over the course of a regulated match. If you must continue to stand up against a boxer who outweighs you (thus, all other things being equal, produces a more powerful punch) and outreaches you (thus, all other things being equal, lands more punches) for the duration of 12 three-minute rounds, the outcome is less in doubt with each successive encounter.
So, I don't think the size advantage of a likely attacker means that "getting better at hitting" is a useless pursuit if you practice aikido. The problem is in how you go about it, and what you hope to gain from it. It is like any other skill: to be effective, you need a good teacher and a lot of practice. It isn't the function of an aikido dojo to provide the instructional and practice time to serve that need -- even if you have senseis or members who have good striking skills (and many dojos do), that would have the effect of robbing the aikido practice.
As for striking being "unnecessary", that's kind of an odd way to put it. Necessary for what? Unless you qualify that, ultimately nothing is "necessary", not even oxygen -- it's just that without it, there are certain consequences. The same is true of striking skills. I have no doubt that many aikidoka view striking as unnecessary, and also no doubt that for at least some of them, it's true -- their aikido is good enough to be the only tool they need if they are attacked. For the rest of us, I think it's wise to consider how to do effective atemi. That does not have to mean learning how to administer a knockout punch, but it does mean going beyond vague and ineffective hand-waving.