So you think that if you buy a $2 coffee in Starbucks this transaction should be registered in all computers running bitcoin in the world? Inegociable?
Who decides what's "important" enough to mandate space in the blockchain?
In general, micro-transactions shouldn't happen on-chain for the single reason that they are impractical, at least under this block size. Ideally, micro-transactions should happen off-chain, not because I say it, but because it is not sustainable; people would rather not pay more than their coffee for a transaction fee.
Yes, I agree with you entirely. Micro-transactions on the blockchain are just impractical and could even cause a congestion in the network and increased fees, among other issues. For these kinds of transactions, off-chain solutions such as the Lightning Network are far more appropriate. Some people actually claim that the only way to scale Bitcoin to accommodate widespread usage is through off-chain methods.