The only reason Steemit has a practical veto on changes today is because the company—at the present moment—holds a lot of stake (regardless of license), which we have publicly committed to decentralizing over time as the platform grows. We don't want to be a government. :)
The stakeholders choose the witnesses, the witnesses choose the software.
Can you imagine the value destroyed if we were to override the community like that? Nobody would benefit from that, especially not us.
If it is not a practical veto, why keep it? What is it protecting?
You have already stated that it protects against forks. But forks are our protection against central authority.
Then why keep the option for yourself to override the community? That's what the clause essentially boils down to. Steemit Inc has nothing to fear from a fork which isn't used. So it's only when the community genuinely diverges from Steemit Inc that this clause ever actually matters.