Could you list some of these consequences? I can think of the obvious reasons like
higher bandwidth and storage requirements, but maybe you have additional reasons why
increasing the blocksize is a bad idea.
There are computational costs of larger blocks as they can be more computationally expensive to validate. Other considerations include the orphan rate, increased potential for fee sniping, larger attack surface for potential DoS attacks, etc.
Segwit destruction will snowball. One miner will figure out it is more profitable to skip verifying signatures. Then two and three figure it out. Then those who don't skip verifying signatures will notice their relative reward rate dropping. Then someone will publish new bitcoin code that makes it more profitable to mine (by not verifying signatures). The less people verify, then the less risk that skipping sig verification would result in the block getting rejected by the network. Then more and more will join the bandwagon until those who verify signatures are a minority and at that point bitcoin gets majorly attacked and starts collapsing.
Please stop spreading misinformation. This "attack" is not just limited to segwit; miners could have chosen to not verify signatures anyways before segwit activated. Regardless of whether segwit is activated, if a miner produces an invalid block because it contains a transaction that does not have a valid signature (again, regardless of segwit or not), other non-mining full nodes on the network will reject that block and the miner will be wasting his time and electricity.