Another problem that 5e has that I should have mentioned is allowing magical classes the ability to poach the things the non-magical characters have as well. If you're a full caster, you have no business having access to Extra Attack. I know people love Gishes (as do I) but it's silly to be like "so my Bladesinger can mix it up in melee with super high AC if I want, but I can't do that, I'm still a Wizard". You should build a whole class around this concept, not slap it onto a Wizard (or Bard)*. I guess it's ok for a class like Warlock or Sorcerer, who have harsher limits on their spell use, but I think it's telling when comparing Eldritch Knight to Bladesinger. It's like, wait, so I can fight good and have 1/3 casting from a somewhat limited pool of spells or I can fight reasonably good some of the time on my guy with full casting and all the best spells?
*I guess since they're sort of built to occasionally hit stuff, Clerics might be ok with Extra Attack, but thanks to how the War Domain functions, there's apparently no budget for it in Cleric subclasses. Or maybe it would make War redundant, I dunno.