If you look globally you will find way more variety in mobile hardware than just 2 changes in 15yrs.
Integrated will never draw zero power, especially as most of the uses you quote as benefits mean it will likely stay powered on, if its integrated OEM Apple have to quote battery life with it in place, if its USB it can be discounted from the quoted battery life.
Of course integrated parts can perform "better", but that doesn't mean the market exists for all products to have integrated mobile.
One doesn't need to unplug a baseband chip for it not to draw power. I'm not sure what gives you the impression that any bit of silicon that's placed on a board has to draw power and the only way to prevent it from doing so is to physically remove it. Turning off an integrated WWAN part is no different to unplugging it :/
I didn't say there wasn't lots of variety in mobile networks around the world. What I said was, there have only been 2 meaningful changes in the past 15 years that would render an integrated part obsolete. If I had a 2G GSM modem built into my machine, the only thing that would render it obsolete (or make me wish I could upgrade it) would be the transition from 2G to 3G.