But there's the rub, they're not more convenient. It's hardly convenient for me to want to listen to music on the way to work only to find I have no battery to do it on the way home. If I need to make an important call I can't. If I want to send a text I can't.
I don't want to have to charge my phone while at work. I shouldn't have to. Time was when a phone could go a week on a single charge, now they can't go a day. Yes, they do more but it makes things far more inconvenient in the long run.
you can get second batteries for most phones for under a tenner...
tbh a fair few of your problems could be solved by reading your phones manual to find the features you want.