I'm sorry but this is absolutely not the case, Milly. The reason that people get defensive is that we have a carefully constructed process that does work (thank you very much!) and is well documented. We talk about it quite often in fact as it is a defining characteristic of how bitcoin is developed which differs in some ways from how other open source software is developed -- although it remains the same in most other ways.
Changes to the non-consensus sections of Bitcoin Core tend to get merged when there are a few reviews, tests, and ACKs from recognized developers, there are no outstanding objections, and the maintainer doing the merge makes a subjective judgement that the code is ready.
Consensus-changes, on the other hand, get merged into Bitcoin Core only after the above criteria are met AND an extremely long discussion period that has given all the relevant stakeholders a chance to comment, and no significant objections remain. Consensus-code changes are unanimous. They must be.
The sort of process that exists in standards bodies for example, with working groups and formal voting procedures, has no place where changes define the nature and validity of other people's money. Who has the right to reach into your pocket and define how you can or cannot spend your coins? The premise of bitcoin is that no one has that right, yet that is very much what we do when consensus code changes are made. That is why when we make a change to the rules governing the nature of bitcoin, we must make sure that everyone is made aware of the change and consents to it.
Everyone. Does this work? Does this scale? So far, it does. Uncontroversial changes, such as BIP 66, are deployed without issue. Every indication is that BIP 66 will complete deployment in the very near future, and we intend to repeat this process for more interesting changes such as BIP65: CHECKLOCKTIMEVERIFY.
This isn't about no one stepping forward to be the "decider." This is about no one having the right to decide these things on the behalf of others. If a contentious change is proposed and not accepted by the process of consensus, that is because the process is doing its job at rejecting controversial changes. It has nothing to do with personality, and everything to do with the nature of bitcoin itself.