If it's choosing an ending, I agree, that does sound awful (I want to be surprised by how something ends), but if it's making a choice and then the show has to

If it's choosing an ending, I agree, that does sound awful (I want to be surprised by how something ends), but if it's making a choice and then the show has to deal with the consequences of that, that could be interesting (especially as it's Black Mirror, which is likely to actively subvert the choice). It's certainly possible to have a singular vision but multiple endings.