segwit 'no witness mode' takes a full node away from being a fullnode and into being just a compatible node.
centralization is where there is only one source of code. so blockstream wanting to be the only source of a fullnode. is them centralizing and then lowering the distribution of fullnodes by allowing a non-witness mode and wrongfully telling them its ok to not accept witness data
as for saying that everyone that wants 2mb is a "classic backer" shows your narrowmindedness..
Narrow-minded? What other 2MB software is currently available?
Regarding the signature chain:
In a nutshell, and IMO, there are two ways to approach the increased cost (upload bandwidth) of increased throughput, all else equal. We can externalize the cost to all nodes -- but then we can expect a drop in all nodes. Alternatively, we can distribute the cost to those who are using it (and who can pay for it).
Can you provide an estimate of the cost for an attacker to exploit the signature chain, if this is a real threat? If you are suggesting that segwit is a security threat, could you provide examples?
If you are suggesting that trust is an issue, please provide some evidence of a potential attack vector and explain how it could be exploited.