I get why they did this, but it does seem to complicate things to me.
Overall, I echo the sentiments you share here. I do have one thing to add though, in response to the following.
"...if this is what we all consider "decentralzied social media" then ... how is it any different from all centralized ones we know?"
It's different because Steemit Inc. does not control the underlying provision of content interchange, and neither does any one entity. Even without them or their consent we can get the social media job done as long as there are still witnesses propping up the blockchain with publicly exposed full nodes. You or I can develop applications on top of that blockchain without having to worry about intellectual property shenanigans or licensing tomfoolery. These two things alone seem quite exciting to me. I may even be tempted to say revolutionary, but let's not be over-optimistic.