I voted that you are not being unreasonable
@Newfluff but maybe I shouldn't have voted at all, as I believe that it is a rather grey area. Some of your issues I absolutely agree with, while others don't seem to be so much of a problem.
Take the cage worry for a start, a small child's pet guinea pig toy should only arrive at the child's home in it's transporting cage, and then be taken out and be treated gently by the lucky child. This (illustrated) guinea pig is obviously going to be a 'house' guinea pig, and have the freedom of the house - or part thereof, but until the pig can be trained to poo in it's litter tray (I suggest an old backing tray and shredded paper from the office - home or at work, and must have been printed on with non-toxic ink), it's little adopter will need to learn to be aware and to clean up any wees or poos that it does in the meantime! But that is definitely only a trasnsporting cage OP for when the little piggy goes to the vet etc.
I do seriously think that anything like keeping toy pets, or babies (baby dolls) should come with a list of care notes, and should not be given to a child until they have a reasonable understanding of their parents vocabulary - with the exception of from birth suitable furry animals. My own wish is that all babies should have at least one of their own well made furry animal toys, and I mean all, I think it is extremely sad that globally there will be so many babies who do not get that opportunity - sorry for the aside.
Obviously most enlightened mums parents will tell their little ones if they start to treat their toys "cruelly" (what would be considered cruel if it was a real animal or baby), eg holding baby upside down, and dunking it's head into a bucket of water/the toilet! My own Dear Mum, sadly now long passed away, once remarked to me when I was little, that she was worried that when I had my own baby I would never dress it, as I kept my own life size baby doll undressed most of the time - I never forgot her saying that, even though I am pretty sure that at the time she said it with an exclamation mark! When my first born was about 13 months old I did say to her "see I have kept him/her dressed - when appropriate!"
Like a PP said, if your little one's baby doll came with it's own milk bottle, and a miniture bottle of - hopefully pretend - whiskey (I'm half Irish, long survive Bush Mills 😍), for the purpose of (pretend) adding some to the baby's milk bottle to help it sleep, then hopefully every single mumsnetter would find that outrageous! My very Dear Departed Uncle gave my first born a teaspoon of whiskey after my child's Christening, when I found out I was naturally furious. My Uncle was born in the 1920's, he was highly intelligent and educated (he could not only speak fluent Latin, but fluent Greek too, he was brilliant at maths, and very educated in, and enjoyed many of the arts - it is such a pity that none of that rubbed off on me 🙈).
The point that I appear to be struggling to make is that depending on a multitude of different reasons, anyone can make important mistakes in regards to child rearing, no matter what their level of commonsense, education, or a myriad of other positive or negative qualities, so I am very much on OP's side for starting this thread, and I also believe that any 'toy' that needs taking care of because it represents a living creature in real life, should absolutely come with care instructions.
Hopefully those enlightened people that I mentioned earlier, would be able to explain the difference between toys and real animals (including humans) to their child, and the importance of still looking after their toy even though it is 'only' a toy. But then I am also someone who is horrified by family and neighbours who think it is ok to pour boiling water on an ant hill, or to cut slugs in half, etc, which is probably why I do find that quite a few aquaintences seem to find me very strange, or far too serious...