The write transaction is the right to free speech , who are you to classify something is spam or useless information, today ordinals are illegal tomorrow every transaction on btc is illegal if it does not go through some 3rd party AML rules 
Right to transaction is right to free speech which is what Bitcoin is all about. 

 "bitcoin a peer-to-peer electronic cash system". It's an e-cash system, not a decentralized monkey-jpeg storing system. 

 That's why data is stored on the genesis block by satoshi himself? 

 Genesis block cannot be mined, it must be manually created, so it's not the same thing.