This is really simple to me.

If you ask all 'anti' fork folks if they hold Bitcoin with an expectation of eventually being part of a large global group of users they will probably say yes (they don't expect to only be able to transact with friends). This is what gives bitcoins value and expectation of higher future value. Therefore holding bitcoins == belief in global user base.

At the same time the anti group wants Bitcoin to remain decentralized. However, nobody has proposed making it centralized.

The anti group isn't arguing this. They are arguing for protection from Bitcoin becoming centralized. However, how to protect Bitcoin from becoming centralized was never spelled out as 'it must never transmit over 1MB blocks'.

It's true keeping 1MB blocks reduces risk of centralization, but so does 1KB blocks. Both of these limits are unworkable for supporting a global user base, but only the 1KB block is more obviously problematic at current usage.

The anti group seems to have a disconnect between present day usage and future usage.

As Gavin said raising the size in line with current capability and expectation that technology at least continues to follow Moore's Law and Nielsen's Law seems a reasonable compromise. What is there otherwise? Not much.