It's more than just the decentralization, although telling "just the decentralization" might sound like it would be something small/insignificant (and it isn't so).
It's also the fact the blockchain doesn't allow entries from the past get modified and it's also the hash rate protecting the blockchain from malicious parties (like double spends).
The blockchain is a really good technology and a lot of people believe that in the future we would get to see it play a part in other industries and not just in the financial industry such as cryptocurrency. There have been so many other ways that is believed that blockchain is going to be useful in the future, although it is not being applied in most of the day speculated areas for now, but in the future we would get to see it play a role as a lot of people have believed it would today.
And for the fact that it promotes transparency and also traceability, and there is no way for anything that is written on the blockchain to be wiped off and be written come that's really helps in security for whatever sector it is being used.