1.) The original vision for Bitcoin was to increase block-size to up-scale. The creator had said this was how it would up-scale.
2.) Segwit is changes fundamental aspects of the code iin Bitcoin, what gives them the authority to make such changes over the original plan?
3.) The core developers are associated with Blockchain (a company) and we think that they have decided to make certain changes based on their influence and that is not impartial.
4.) Hardforking to bigger blocks is only not safe because Core have turned so many against the idea so it is hard to get consensus. Two "bitcoins" never occured in the past and historically we always hard forked without any issues to raise the block size.
5.) Segwit does not solve the scaling issue right now, it relies on later changes which might not work and so we will have to hardfork to bigger blocks anyway.
1.) BU team is too small, far smaller than ours, they work privately and don't peer review – in short, they are producing sub par work in comparison to ourselves and that is risky in itself.
2.) Segwit fixes a malleability issue of Bitcoin that has always been present (Don't know what this is, but from an online search some think this needs to be fixed).
It fixes this issue, but it also makes a couple changes to Bitcoins code that gives us some potential scaling options in the future. It also makes some minor changes now that gives us time to implement a new long term scaling solution.
3.) The problem with the original vision of Bitcoin scaling is that big blocks make it very hard to download the blockchain and run a node.
A node is what allows normal users to cast their vote on Bitcoin which keeps it decentralized, if the block became too big normal people could no longer run a node.
That job would then become solely the role of data centers or companies and takes out the "vote" of the average user.
We therefore propose we need a new scaling solution that does not ultimately lead to this situation occurring.
I've been reading about this situation for a long time now, never pretending to know what is going on fully. However I now think the above is essentially every VALID argument on both sides.
Simple logic dictates, allow Segwit to have a chance, allow for a new way to scale that keeps everyday users able to vote. If it doesn't work then hard fork to bigger blocks in a couple of years and continue working on another solution.