So BU is the answer? where only a big mining farm owning almost half the hash power wants to increase the block size as long as there are transactions in the mempool, but would they just and only change the blocksize without changing anything else?

to remove long term moral hazard, core block size limit should be made dynamic, put in the realm of software, outside of human hands.

implement a permanent block size solution once and for all, that will keep the block size limit above market demand. There are several options, such as Stephen Pair’s flexcap proposal.