The ring isn't a "real fight"...
To fight for the ring isn't "real training"
The supreme martial art to win over all other martial arts is this:
If you fight for the ring, then sure, train for fighting in the ring, but dont ever confuse it with the ability to properly defend yourself out in the street.
Its true that by fighting in the ring, you gain some pretty useful abilities that could come in handy in real life situations. Like learning on how to predict a opponents body movement and take a punch amongst several.
But for every advantage you gain, there comes drawbacks. In real life situations you wont have the luxury of being able to study tapes of previous fights by your opponent to learn how to predict his tactics.
In the ring, your opponent wont have friends to come to his aid. In the ring, your opponent wont suddenly slip on some knuckle dusters, pull a blade or swing a bottle to your head.
Tons of things can happen, and all of a sudden all fighting in the ring has done is given you a false sense of security.
Morihei Ueshiba himself didn't approve of competing in Aikido.
He didn't create Aikido to teach us how to "beat people up"
He didn't even create Aikido to teach us self defence-
He created Aikido to promote peace by teaching methods on how to enforce it.
But not force peace by "breaking someone's arm so they calm down"
or even "I WILL break your arm if you don't calm down" but "I CAN break your arm if you don't calm down"
In closing, if anyone wants to learn to fight in the ring.. go train Boxing, Judo, MMA, Shodokan or BJJ or whatever. DON'T go train (regular) Aikido and expect it to adapt into a Sports variant just because you want to "try its effectiveness".
That's my view of Aikido anyway, it may be in conflict with yours, but its how I perceive it and the reasons why I train it.
And I train Iwama style Aikido and it's not known as "Lumberjack Aikido" for nothing.. we can get pretty rough at it sometimes.
But we start carefully in the beginners level and then gradually increase resisting and countering techniques.
"if it don't hurt, it's not working" as we say.
I'll say it one more time, then never again. Sparing is not competing. It never was, it never will be. Sparing is not ring fighting. It never was, it never will be. Sparing can incorporate all the things you have talked about. You can bring in weapons in sparing, you can bring in multiples in sparing, you can do 95% of everything you can do in the street in sparing. The parts you can't do are of little consequence to good technique.
Most excuses listed for not sparing a really not valid.
1) Too dangerous - I do it almost every day without injury
2) Age - I know 50 year old guys who spar, sure it's not at the same crazy levels young guys spar, but sparing can be at different levels just like everything else.
3) Uesihba doesn't want competition - Sparing is not competition. There are no winners or losers in sparing. Only good and bad techniques.
4) Rules prevent realism - If you can punch someone in the face, it is safe to assume you might be able to eye gouge them. You never actually eye gouge someone when you are not sparing, so why does it matter you can't eye gouge while you are sparing. Weapons, multiple attackers, objects and uneven fields of play can all be added to sparing. I had a guy once try to choke me with his handwraps, it was funny and startling at the same time. A very hidden weapon. I of course choked him out with his handwraps.
5) But we are a weapon art - So spar with weapons, plenty of other arts do. Kendo guys even have a good set of armor to allow you to hit each other with sticks.
6) My art is not a sport - No one has said it has to be, sparing is not competition, there are no winners or losers. You simple use it as a tool to learn about what works and what needs work on your technique. It will give you insight into yourself and your character. All very budo to me.
7) My art is about killing people, not about fighting - Well, that is all fine and dandy, but usually sparing reveals those deadly techniques are not as easy to land as you think, and usually not as deadly. See nerve strikes as an example.
The list goes on and on. The only legitimate reason for not sparing is this
"I just don't want to."
That is fine, but you need to understand what probably is missing from your training. The pitfalls of not sparing and the issues it can create. I won't go back into that, it is covered well in the posts above. Suffice to say I feel the dangers of not sparing outweigh the dangers of sparing.
It's great if you want to do some kind of exercise that makes you feel spiritual and good inside. I would never want to take that away from anyone. But there are people out there who will one day be instructors (or are instructors now) preaching that they know how to teach someone to defend against an attack. Yet they have never, their instructor has never, their instructor has never, and their instructor has never been in a fight. Not even a fake fight like a sparing match. How can anyone even think that they can teach you to cope with the stress and adapt to the situation of a real fight when they haven't even been in the stress of a fake one.