And 98% of nodes right now can support 4MB blocks without a problem.
I'd like to see the testing methodology used in order to draw to this conclusion. IIRC there was some 'research' being done by some team a while ago, stating something like this (although I'm unsure about the specifics and can't find it). Please post the source if you are able to.
I recommend 10mb size maybe its enough already.
That number is just arbitrary and useless.
1mb is clearly not enough but 10mb would be a shock to most systems.
A tenfold increase in resource usage is definitely a "killer".