1. "Not as useful" is subjective. In the last six years I don't think I've ever plugged anything into any of my mobile phones 3.5mm jacks. Bluetooth audio has been around for a long, long time and I've always used that instead. Meanwhile, I've used apps that require, or would be enhanced by the presence of, a barometer pretty much every day. Weather trends, hiking, skiing, and lots of other activities other than playing Xbox in your mother's basement make a barometer very useful.
Old-fashioned 3.5mm jacks are so obsolete that in many Asian nations, they're only used for holding "mascots" — Little cartoon charms.
2. If you think you can fit both in, then you should patent your great knowledge and make millions. But you won't. Because you're not an engineer, just another internet troll. I'm going to guess that the fleets of highly paid, highly trained engineers Apple has on staff know a little more about how the iPhones are designed than some random loser who is such a total loss he has to post AC.
How's that floppy drive working out for you, Mr. Dell?