1) There is a 'buglet' in Bitcoin that means that you can construct a TXN that uses a lot of time to process / check. Let's not worry about what it is but agree that it exists. The larger the blocks the easier it is to construct this TXN, and IF we had 2MB blocks, right now, you could bring down the network. This issue is fixed with SeqWit. So Core thought, let's introduce SW first, THEN we can make the blocksize bigger. Safely.
not fixed
because
core v0.12 buglet (quadratics) 4k tx limit (10 seconds buglet delay per tx) block limit 20k (ability to have 5tx of the the txsigop limit)
core v0.14 buglet (quadratics) 16k tx limit (8minutes seconds buglet delay per tx) block limit 80k (ability to have 5tx of the the txsigop limit)
the segwit 'activation' itself solves nothing.
even if 99.99% of people move funds to segwit keys to DISARM themselves from causing (your buzzword buglet) quadratics. 1 person can make just 5 quadratic transactions to use up all the sigop limits and cause 40minutes of validation delay instead of 50 seconds.
the solution is not segwit. the solution is maxtxsigops to remain at 4k (less than a couple years ago) or bring it down further... definetly not raise the limit to allow it to become more of a problem/ attack vector