Then the easiest solution is changing the flavor text, because after all that is not what the class crunch tells us (except for the 3 instruments they gain at level 1). Subclasses of splat books actually have more musical abilities, but in the PHB both subclasses support the Idea of a loremaster/rogue or warrior/leader.
It is also not what I have seen in play for the last few decades... the bard was never the muse. They did perform on stage sometimes, but their roguish behaviour and their magical one always stood in the foreground.
In ADnD they were correctly classified as rogues. The 3e bard was more musical I admit, but 5e puts them back were they belong.
I am not totally against changes. But relegating them to half-casters and adding musical abilities to compensate is the wrong way.
As others have already suggested, the warlock model could have worked well for the bard. Imstead of invocations they could have learnt bardic secrets that could be magical, musical or skillbased.
They would have to do more stuff than just casting spells during an encounter, but their highest spells are still (nearly as) powerful as other spellcaster's.
No, again, as I said in my last post, "Magical Muse" is supported more in the 5e Bard's mechanics than "Jack of All Trades" is. It's not just the fluff text that supports bards being a "Magical Muse", it's also a ton of mechanics. Song of Rest, Musical Instrument Proficiency and Spellcasting Focuses, Bardic Inspiration, Countercharm, and a lot of their spells and subclasses are all either explicitly or implicitly connected to their musical or poetic nature. "Jack of All Trades" is literally only supported by 2 mechanics (Jack of All Trades and Magical Secrets), while "Magical Muse" is supported by
waaaay more.
5e's Bards are "Magical Muses". They're not all Musicians, some of them are poets or other storytellers, but all of them are connected to the concept of a "Muse".
I frankly don't care how they were in previous editions. If they used to be a Rogue prestige class, that's fine and dandy, but 5e doesn't do everything that previous editions did. Elves and Dwarves are no longer classes, THAC0 no longer exists (except as a clown NPC), all classes level up using the same XP table, d20s are used for basically everything, Paladins are no longer required to worship a god or be Lawful Good, and prestige classes don't exist anymore.
Furthermore, probably the single most well-known Bard PC in the modern hobby (Scanlan) perfectly embodies the idea of a "Magical Muse". Like it or not, 5e Bards are magical muses; mechanically, fluff-wise, and in popular culture. They're not Rogues, they're not equally good at literally every role that can be played in the game, and D&D is not completely beholden to its past for class or race concepts in the game. Things can, do, and have changed, and that's okay. Things will continue to change, and that's also okay.
Denying that "Magical Muse" is in the core of the 5e Bard class really seems ignorant to me. It is. They showed it in the fluff text, in the mechanics, and the most popular characters and stereotypes of the class all fit the idea of the class being the "magical muse". It's just a fact.