I'm not sure.
A good question to ask is why can't my particular teacher replicate the various feats ascribed to the founder of the art on trained athletic people from outside the art. You also might ask why you do all sorts of wacky exercises that seem to have no real purpose or connection to the waza you preform. You can either come to the conclusion that the founder was a super special guy, that it was all fake, or that something is missing. I used to think it was 1/2 for aikido and other arts I studied, now I tend to believe it's #3.
Once upon a time I trained in aikido and I never met anyone who could move me around with essentially zero resistance or repeat the various feats ascribed to the founder. These guys didn't force me to move in particular ways due to pain compliance or moving in a particular way was expected by your partner. Most of what I learned in aikido and various other martial arts was predominantly technique based, yet applying these techniques on IS/IP people simply didn't work. They didn't use better waza nor superior physical strength or timing like many high ranking practioners I had previously trained with.
When you start to get some exposure to the concepts talked about, you start to see how far off you (and possibly your teachers) were in the past because they simply didn't know. The various words and descriptions take on new meanings as if your "eyes were opened to budo". (Who said that?
As for why aikido? Well its been answered before, but the whole IS/IP fits in rather nicely. Plenty of people have argued that aikido simply doesn't work on resisting opponents. IS powered aikido appears to work according to people that attend seminars by various MA people. A reasonable conclusion is that IS people can make aikido work, and might have a better understanding of what aiki is.
I asked that question as you proposed in your first paragraph, about some teachers, not mine for he could.
I could also see the founder was a special guy xo comparing other teachers to him was a bit silly no?
Now doing all sorts of wacky exercises that don't connect to waza? That's a false statement I'm afraid.
Your final point in that paragraph says you did various martial arts but couldn't effect them on ip guys. Now that could be an interesting point if you mean that on all other people you could.
Second paragraph says basically you did some Aikido but never met anyone like Ueshiba. Not surprising.
Finally why Aikido? Well the whole ip thing would fit most martial arts, especially ones with holds etc. wouldn't it?
So in conclusion, for those who never found the whys of basic exercises and their relationships to waza etc. then it would be useful up to a point, indeed for those it would be eye opening no doubt.