A miserable pile of (Magical) Secrets! But enough talk!
They didn't have as much spells in 3.X for example (although more than an arcane trickster, they were "2/3 casters".) Is magic really core to the concept?
Usually I say no to this question--I consider Rangers and Paladins significantly improved when they
don't cast spells, but have other forms of supernatural power--but for the Bard? Yes, absolutely. The whole point of the Bard is that they do all the things. They're the equivalent of Red Mage from Final Fantasy (or, rather, Red Mage is the equivalent of Bard, since D&D very much came first.)
The assassin had spells in 3.X...
And, as above, I think that that is sad. Proper spells should be one important, but not
hegemonic, branch of supernatural power.
Some classes should be focused on it. IMO, those are Bard, Cleric, Druid, Invoker (a 4e class), Sorcerer, Summoner (a PF class), Wizard, Warlock. Possibly also Artificer and Shaman--I can see those going either way. But Assassin, Avenger, Monk, Paladin, anything psionics-based, Ranger, Swordmage, and Warden should all do things that
aren't neo-Vancian slots-and-levels spellcasting. That doesn't mean they shouldn't have supernatural powers; instead, it means that whatever supernatural powers they have should function differently, preferably more closely tailored to the theme of these classes. (Notably, most of those which I think should use neo-Vancian casting are pretty "big tent" classes with multiple divergent takes under one roof, while most of those I think
shouldn't do so are more inherently tightly-themed, with subclasses being more about focus and tone than about playstyle shifts.)
Lastly, I'll note that one of my players wanted to play a "bard" but they didn't want all that heavy spellcasting. I helped them make an AK with the entertainer background...
For someone who wants a character that is like that, awesome. Opting
into that is great, and I would 100% approve of a "soft multiclass" option for a Rogue with a dabble of Bard. Making it so everyone must run with that--and, moreover, cannot opt
out of it--is kind of a problem.
Or, to put it a different way: By this standard, the Eldritch Knight is a Wizard replacement. No need to
waste space on a full Wizard class when the Eldritch Knight is good enough!
Providing "soft multiclass" options of all kinds is great. It isn't a good substitute for true classes. That doesn't mean we should hare off and make a class for
every possible concept, because that would be silly. But it's just as silly, IMO, to pass off "soft multiclass" options as though they fully cover an extant class.