You really sound like you're still trying to reason yourself out of the need for a different training paradigm rather than getting out and just feeling it. That's like having a discussion about whether the stove is hot or not, just go feel it and see.
Traditional muscular strength can certainly make you very powerful.
IP doesn't make you invincible or guaranteed to be awesome at anything you try. An amazing tennis player probably has tens of thousands of hours developing their game. If you replaced those hours with a similar amount of time developing internal power, they wouldn't be as good of a tennis player.
One could just as easily make the argument that if you wanted to be a good fighter, you'd be better off training in a boxing or MMA gym than you would doing Aikido. You'll develop much better fighting skills much faster and have something that is more "streetable" in short order.
But you won't have aiki...
That's what we're getting at with the training paradigms many of us are persuing. We don't want to just be a better fighter (although that's certainly part of the process) we would like to approach the skills that we have read about that enchanted us in the first place. *In my own view* the training paradigm that most people follow is very much like going to the gym and doing circuit training to develop aiki. The training model hasn't worked. Rather than develop internal skills that lead to real aiki (the stuff Sagawa and Ueshiba talked about) it has developed traditional muscular skills which is why it has always seem lacking when compared to what we read about the founder and his early generation.
When I first felt Rob John or Ark, my brain freaked out. They just didn't *feel* like other people. At the time, I probably had close to 40 lbs on Rob and had trained in the martial arts for a longer period of time, but I couldn't even push him backwards. He *felt* more solid and less affected by my movements than Hiroshi Ikeda did (just to put an example out there). No, I'm not saying Rob is a better aikidoka than Ikeda sensei, but he *felt* different. When one of our guys first felt Dan, his immediate response was, "You're f****ing weird man!" This was from a very skilled, very big, very well trained guy! Asked later what he meant, he just said, "That guy just feels fricking weird!"
One of the reasons I don't post much anymore is I just don't generally feel the need to constantly be justifying my training decisions. They're my own to make, just as yours are your own to make. Train however you want. But I don't have an obligation to convince anyone that my training paradigm is the one worth following. People will get out and feel it and decide for themselves, but no amount of written copy will ever convince everyone of the value I feel there is there. You make the effort and get out and feel it or you don't.