To be bluntly honest, yes, Paladins have had a close relationship to Clerics, so having them both be casters is a piece of mechanical symmetry that I like. It's why they also share Channel Divinity, it strengthens their common bond as wielders of divine magic.
And I don't agree that this is a simple thing. Monks use ki ... but that is their core mechanic and the 2014 Monk needed some of the most upgrades and revisions for 2024. Sorcerers also got a massive revision because the initial design was too stingy over their own Sorcery point resources. Warlocks continue to be a point of contention because of how some tables manage their short and long rests. So the idea that "this ain't no thing" ... well the classes cited indicate it was and is.
Paladins have more types of resources to manage than other classes, it's true. Which is why I'm in favor of reducing the complexity by not making all these things unique for the sake of uniqueness.
I'm not against classes having different mechanical expressions, if this was an argument that Artificers should not be half-casters and have their own Infusion casting system, I'd agree it's an idea worth exploring. Part of the draw, to me, for Psionics (a base Psion/Mystic class, though, happy with the Psionic flavored subclasses as is) is that Psionics isn't just spells without components so some mechanical differentiation is to be expected.
But given that Paladins have history as spellcasters, are tied thematically to another spellcaster, the Cleric, and are a complicated class with a lot to manage already ... I haven't seen a solid reason to change it.