I wondered why no one still mentioned the following counter-argument:
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.
That is not an argument against "2 MB + Segwit".
Proposals like Lerner's
"Segwit2MB" would activate the 2 MB hard fork after the activation of the Segwit soft fork. Maybe Lerner's 6 months (if I remember right) as "grace period" is too short because maybe until then most people would still use legacy transactions, but 1 year would be surely enough. We would then activate Segwit in mid-to-late 2017 and 2MB in mid-to-late 2018. Jihan as far as I remember mentioned the Hong Kong Agreement several times, so he should be happy with this solution.
What wrong with do both as hard fork? Wouldn't segwit hard fork be better than soft fork?
I assume if hard fork for both then there is a need to allow legacy txs to be converted at a later date. ie. 10 years.