Mark, the point you are trying to make is not lost on me, I know that the "rooted" punches do loose something with regards to mobility.
If the striking arts were meant for confronting armed individuals, they might move differently to cover the larger amounts of space between combatants. But they're not. Consider that any armed combatant is probably wearing armor too, which makes the idea of trying to punch them more than a little silly. By their very nature, karate and such are designed for unarmed and unarmored combat.
On the other hand, throwing arts are usually indirectly descended from arts meant to help disarmed troops deal with other armored foes trying to beat them up. Armor doesn't keep you from getting thrown or a joint broken.
So, the ma'ai for striking is significantly closer than anything that happens in Aikido. Aikido practitioners try to keep greater distances in order to force attackers to throw the kinds of attacks that are easy to throw. And that's just peachy keen. Controlling ma'ai is a very important thing to practice and learn how to do.
So perhaps it makes sense to have some of those people around who stand way back and try to hit you with punches that leave them half falling over. However, we should not mistakenly say that that is a good or correct way of punching to generate power. And, since it is harder to throw someone who is punching like that, then we should practice that way at least part of the time to try to better ourselves.
I can understand your frustration with some people who have done strictly kata-based striking arts, though, since I have seen a number of them who put no power, weight, or momentum into their strikes beyond what is neccessary to put their fist forward. These people may be really really tough to throw, but their punches also wouldn't do more than sting a little.