On one hand you are right, it's a huge benefit to developers as they are able to create new services that leverage the strength of the existing network. Such as Peertube getting subscription and commenting features from other servers for free, and it “just works”. Imagine a youtube competitor wanting to leverage Twitter in the same way. Highly unlikely that it would be allowed, and even if it did, the integration would be Twitter-specific.
On the other hand, (at least some) end-users see decentralisation as a huge benefit, and at least in my case it gives me confidence that the whim of a single company can't ruin the experience for me, or even take away the platform altogether.
Most people may not consider this, but some people definitely do. And hopefully that number will increase over time.