if asked to choose between the two, I prefer decentralization because that is the main purpose of bitcoin made by satoshi, yes even though developing blockchain technology, but still the main goal is to decentralize everything.
there are also many cryptos that use blockchain technology that is still centralized.
or there are some countries that intend to make their own digital currency and be controlled by them.
I agree that Bitcoin should focus on decentralization, but blockchain technology is not necessarily. Blockchain technology has other applications besides currency.
Bitcoin doesn't even focus on the decentralization because it's already decentralized. Bitcoin needs focus to the development of the scalability solution and no more. As bitcoin itself has already considered to be utility coin. Blockchain is necessarily caused by it has become the core of the crypto to run its own network. Blockchain is a critical part from the crypto. you must understand it better.