Bazaar of Baghdad is the problem, and would be easily restrictable if not for its iconic status implied by the Forsythe tweet, it would be removable. Since it isn't, all we have left are mitigating measures.
I think this is the part people have an issue with. I just don't buy that bazaar is "easily restrictable". By the numbers bazaar decks just aren't good enough to support the claim that they need a restriction. The basis of the OP is that results aren't everything, which I can grant you. However, if the main other factor is fun had by the people playing, it hard to get objective or far-reaching about that.
Your fun and my fun are different. I don't believe there is a consensus about bazaar and fun. There is no massive outcry about non-matches as there was with Trinisphere (which by the way exceeded dredge in metagame percentage at the time of the "no fun" restriction). There is no time constraint, like there has been with Top in multiple formats. So what is the basis, the only thing that it appears you can be arguing for is your fun is impacted. I think it is perfectly valid to say that, but I also believe that is not a sufficient argument to get a card banned.
I also think more cards from shops would be banned now because for many people (dare I say more than dislike dredge) playing against artifact prison pieces is their least favorite thing in magic, but I hope that doesn't happen. Side note: The thing i have actually heard most in playing magic for 20+ years is "counterspells aren't fun", I hope the people that control the B&R list for vintage don't get wind of that.
Tinker without power seems a lot worse, since you are way less likely to have the 3 mana and the artifact in play, even if you are playing null rods to make up for some of them. Powerless + null rod oath can be a thing, i would lean into the mana denial and also play wastelands/strip mine.
That being said, where do you play that proxy vintage isn't an option? Everywhere i have ever played (besides champs, and maybe 1-2 other big tournaments) are at least 5 proxy if not 15+.
Are you actually asking to explain you the reasoning behind the addition of Lavinia or are you just criticizing or shocked that people are putting Lavinia where she belongs, in a aggro control deck?
Let me put it this way, while the way to "make her shine" might be in a deck with a bunch of creatures, the most likely way for her to be successful is in a deck that is already powerful, using her as another angle of attack (see the decks from the past week's VSL) rather than in an archetype that hasn't been traditionally successful in vintage, in which it has some dyssynergy with the most previously successful card in the deck in Thalia.
Maybe this is the right shell, but I don't think by any means we should take for granted because Lavinia is a creature with the human type that this is the shell that makes the most sense. As you said "an aggro control deck" might be the best shell, so why not start with the best aggro control deck in the format in Xerox as a home.