I get it and I think that's fine but since the cost of storage is dimishing and the speed of internet is going up why not increasing the block limit also?
Storage cost and internet speed are only part of the issue, the other part which is more important is the computation cost, which is the CPU and RAM you need to validate each and every transaction.
With that said I have never been against increasing the block size. Ever since 2017 I've been saying we need to also increase the size alongside everything else we do.
And could you explain why a spam attack would magically cost a lot more if the block weight is 4MB or less?
I emphasized on having the cap (having a maximum size for each block) not on the value of it.
This value has to be close to the needed capacity but higher than it, that way it can ensure that if someone decided to spam the network they go over that capacity and end up creating a fee market that costs them a lot of money to sustain the attack.
4 MB weight has been close to that needed capacity but I believe we have surpassed that for some time now, which is why we keep seeing big fee spikes regularly.