Other than a mindless fearr of a hard fork, give me 1 solid reason based on logic against a block size increase.
1) Security risk of a DOS due to quadratic validation problem.
2) No hard fork experience.
3) High risk of damaging merchants and businesses that do not manage to update in time (if the activation parameters are improper such as with Bitcoin Classic).
4) Higher storage cost.
5) Higher bandwidth cost.
Even if we disregard the 4 latter, the primary issue is still the security risk.
1) You could limit the transaction size while still increasing the blocksize.
2) ETH did fine.
3) Few shops actually directly accept bitcoin without an intermediary. Those intermediaries should be bitcoin-savvy enough to prevent damage to the merchants. Those merchants that do accept bitcoin directly probably know enough about it as well.
4 & 5) The increased costs is only marginal. Most people already have internet that can easily support much bigger blocks than 1MB, both upload and download, without even affecting regular browsing behavior. And most people have plenty of room on their hard disks, even if they don't a 1TB hard disk will go a long way (lasts for 19 years with 1MB blocksizes assuming they are all full and are never once pruned in those 19 years). So obviously there is room for significant improvement without being cost-prohibitive to most people. In fact, a vast majorty of people wouldn't even notice the effect.