Hello there, From my understanding security is a major point but also you want to consider the $$$ factor. Increasing the block size decreases the blockspace scarcity and therefor the subsidy / tx for the miners. The idea of increasing the block size was to lower the fees for transactioners. But in a near future, these fees will be what « pays » the miners. Segwit was a way to decrease the « weight » of a transaction, allowing fees to be a little cheaper. Two options : one led to a hard fork, the other one to a soft fork. The difference : one implied to chanfe satoshi nakamoto principles, not the other one…