Every full node must download the full blockchain (prunable or not!).
Every full node has consented to download and store financial transactions.
NOT every full node has consented to store anything else
My 15GB copy of the blockchain contains an estimated 5GB worth of un-prunable
gambling transactions, and I'm pretty unhappy about that. Are Satoshi Dice transactions "financial transactions"? Are Counterparty investment derivatives paid in bitcoin considered "financial transactions"?
Who are we to judge? As someone who runs a full node, what I'm agreeing to is to support the blockchain and the Bitcoin protocol itself, no matter how it's used. What's objectionable is when the Bitcoin protocol itself shifts beneath our feet because the core development team is making these judgements on everyone's behalf.