1. Most of the use cases being discussed here are irrelevant for the average iPhone user. Charging and listening at the same time is not a thing for most users. I know there are perfectly reasonable scenarios where it is useful, but most people don't care. Regarding battery life: personally, I use my iPhone quite a lot, often with bluetooth headphones, and I have had to charge it only once or twice during the daytime in the last two years. If you play a lot of games, or use GPS intensively for a few hours, then battery life could be an issue. For the average consumer, I don't think it will be a major concern.
2. OTOH, in the last few years headphones have become a very, very big market. They are a huge status symbol for teenagers and early 20-somethings. If you've saved a lot of money to afford a pair in that stage of life, the headphone jack is a big deal. It's not going to be "cool" to carry around an adapter all the time, and regardless people will hear "no headphone jack" and be annoyed. That demographic seems key to me in maintaining Apple's market lead over the long term, i.e. trend-setting young people.
Overall, I actually think that (2) will be a very big issue. Whilst I am of the opinion that wires are horrible in general, Apple may have misread its market here.
