Honestly yes, Paladin is 1-2-3-4-5-6-7. I know it's not a perfectly aligned combo, there are micro-optimizations, but you could fold it into one button at ~no loss of gameplay depth, and that's always the smell test as to whether the extra buttons existing add anything to the gameplay. They don't.

I would fold it like this, tbh:

* Remove the entire Atonement chain.
* Add increased manaregen and damage to the main 1-2-3 chain.
* You get 1 charge each 1-2-3 combo. However, you need two charges to cast an instant spell.

Done. Functionally it behaves the exact same, even down to how you mentally use it, but we've cleaned up one button. Spell damage can be bumped slightly to compensate for the tiny burst-loss of not having 6 available to save for burst. Which also removes one quirky interaction that just shifts focus away from spell usage during burst, tbh.

Now I would not even consider that "Paladin gets a change". The above consolidates buttons, but it doesn't consolidate gameplay. It's 100% the exact same gameplay, but with needing one less hotbar slot. If I were allowed to go further, I'd want to "rescue" the Atonement animations because they're cool, so I'd do:

* As above, but without the damage/managain increase to 1-2-3. Yes this means we lose mana, rapidly.
* Goring Blade causes a 30s DoT.
* If using 1-2-3 on a Goring Blade target, each attack becomes one of 4-5-6, including the damage gain, the mana regen and the animation.

This of course causes actual gameplay change, hence why it's not a "might as well" as the first change above. But it also preserves the animations, while still freeing up a hotbar button.

Though as far as saving hotbar goes, first make 1-2-3 an autocombo tbh. There's no reason not to do this, beyond some very old very grump users thinking that if they had to have their screen be 50% hotbars, everyone else has to, too!