Now we have:
3. Use it like a cloud storage to save stupid low resolution images
4. Use it like a notebook to save useless jsons for useless imaginary tokens
As the age old saying goes: its not spam as long as the person doing it is paying the fee. Same goes for any other transaction done on the chain.
As for it causing issues for Bitcoin, sure that can happen. Solutions must/will be found to combat this, or something else will take over the day to day transaction part of the chain (which is already kind of has)