1) But such a thing that you desire, can never exists, as long as you have any property that allows for custom data to be attached? IMHO us removing the limit anyways won't do anything and it's worth the risk, BECAUSE we can always come together again and decide that this was a bad idea and we should roll back. It's like when you dig a pond for you to bath in, you also have to live with the birds that will find this pond and drink from it and maybe shit in. It's just something that is there and what is there gets being used. It's the most natural thing. There is no pool/pond in the world, that is only used by humans, even though the sole purpose it was being built, is to bath in it. Other animals and species find other use cases that do not get in the way. Bitcoin knots is - apart from merging what they should not merge just like that - the chemicals you would throw into that pond to keep others from using it. I myself like a natural pond, I don't like pools with chlorine and so and I don't care if a ducks takes a dump into it. This is not my world, it is OUR world and we can and have to live alongside each other. A bird will not come to the pond if a human is in it. The economical incentive is not worth the risk. But if no humans are there, it will take a bath and take a sip.
2) Nothing is forever. Initially, there was no OP_RETURN limit, then it got implemented and now it is being removed again. If we find that this was a bad idea, we aren't fucked, we can just remove that part from the code again.