Let me take a pass at explaining how I see this.
1) Code changes to Bitcoin Core that don't change consensus: Wladimir is the decider but he works under a process that is well understood by developers on the project in which he takes under reasonable consideration other technical opinions and prefers to have clear agreement among them.
2) Changes to the consensus rules: As others have said, this isn't anyone's decision for anyone else. It's up to each individual user as to what code they run and what rules they enforce. So then why is everyone so up in arms about what Mike and Gavin are proposing if everyone is free to decide for themselves? I believe that each individual user should adhere to the principle that there should be no changes to the consensus rules unless there is near complete agreement among the entire community, users, developers, businesses miners etc. It is not necessary to define complete agreement exactly because every individual person decides for themselves. I believe that this is what gives Bitcoin, or really any money, its value and what makes it work, that we all agree on exactly what it is. So I believe that it is misleading and bad for Bitcoin to tell users and business that you can just choose without concern for everyone else which code you'll run and we'll see which one wins out. No. You should run the old consensus rules (on any codebase you want) until you believe that pretty much everyone has consented to a change in the rules. It is your choice, but I think a lot of people that have spent time thinking about the philosophy of consensus systems believe that when the users of the system have this principle in mind, it's what will make the system work best.
3) Code changes to Core that do change consensus: I think that Wladimir, all the other committers besides Gavin, and almost all of the other developers on Core would defer to #2 above and wait for its outcome to be clear before considering such a code change.
I'm sure my description of point 2 is not the most eloquent or clear, but maybe someone else can try to elucidate this principle if they've grasped what I'm trying to say.