Why they are doing these massive spam transactions?
Because they see potential profit from the Ordinals NFTs and also the BRC20 tokens. It is just like asking why there are ethereum (fungible and non fungible) tokens transactions.
Sometimes I feel like why those stupid weirdos spending 30K sat to send 1K sats? Does it make sense?
I guess you are referring to the NFTs because if it is BRC20 tokens, you can see that the fee is used to transfer tokens just as bitcoin is used to transfer bitcoin on the bitcoin blockchain. You can see coins like ORDI, SATS and many BRC20 tokens sent using bitcoin as transaction fee on bitcoin blockchain.
I don't think developer intentionally allow it. IMO it's more accurate to say developer didn't expect people would try creating token on Bitcoin again since old token (such as USDT) on Bitcoin isn't popular.
I can be wrong but I always think that bitcoin developers knew about it and they made made Ordinals to exist intentionally, although not all the developers. That is why some developers are now supporting it while some are against it.
Why I said they intentionally allowed it is not because they are not aware of BRC 20 tokens and minting of them. They knew about the Javascript inscription, not like they don't know anything about it, they know and instead of them to soft fork if and release an update to clean that bug, they didn't and live it openly for everyone to mess around with Bitcoin network, if it was another error they see in the network, they will be quick to solve this but because this particular involved transaction fees that compensate the miners, they let it be.
Do you mean that the developers knew about it after miners are already making money through Ordinals NFT and BTC20? Any improvement that will change that will make miners to either support or against it. Developers can propose but miners have the power in something like. No miners will support any developer that againsts Ordinals because they are making money from it and they will be the one that would win.