A blocksize increase does not guarantee that on-chain fees will be low, and your precious BU does not guarantee that miners will even want to create larger blocks once they have the power to, instead of using smaller blocks to gain more fees.
That's your argument? "Raising the blocksize is a pointless incentive, therefore we should prohibit it?"
You can't have it both ways: On one hand argue that "oh no there will be no fees and no security if we have big blocks" and on the other hand say "fees will be high anyway".