I'm hoping the next edition will make armor and shields a bit more complicated again. I also don't like how investing in 16 Dex doesn't give you any defensive benefit with Medium Armor and you're better off with Heavy anyway.
Well... it's useful when you take the "Medium Armor Master" feat into account, since that feat allows you to apply a DEX mod of +3 instead of just +2.
But yes, the armor system is overly simplified and was much better in D&D 3.x.
Which Fighter is going to waste a feat just to be on par with Heavy Armor they could already use anyway? Especially since you also have to invest in 16 Dex for MAM.
The potential Stealth benefit is the only carrot. I don't like how you're railroaded into going all-in on either Str or Dex, and Medium Armor is obsolete in the middle. Would be cool if high Str AND Dex was somehow viable as well as a more defensive and versatile build. Say a High Elf Fighter with high Str and Dex at the cost of lower Con.
Speaking mainly from a PnP point of view: It depends on how I envision the character in question. For example, my PnP ranger is using a chain shirt. Why? Because that's how envision him, even when betters armors exist.
Besides... clerics, druids, rangers and barbarians may be using the feat as well (especially if they're variant human and can take it at level 1). Not everyone is interested in min/maxing, so there are plenty of uses for the feat even as a fighter.
