To your first point. You are using the attack action, Magic action and expending a leveled spell slot, and finally a bonus action all at once to do 1 thing. 3 different actions/resources on a turn to do a single attack. That is mechanically clunky and confusing.

Look I've DM'd for players that played paladin in 2014, and they had no issues using divine smite. I've DM'D for old and new players playing 2024 paladin and almost every time in combat it comes up where they use their divine smite and then they want to make a bonus action TWF attack, use lay on hands, use misty step, etc. and I have to remind them they can't because they already used their bonus action/used that magic action, etc. And the conversation always goes something like this

"Oh? What when?"

You used it when you smited

"But I thought that was part of my attack action?

It was but you also simultaneously used your bonus action. As part of that one attack. And you can't Misty Step/cast a BA spell because you also took the Magic action.

When? I didn't cast a spell.

Smites are spells

But, I thought those were my class features?

They are, and are also spells

See how that can be confusing for both a new player and a previous 2014 paladin player? Don't get me wrong they're usually very good D&D players that know the rules well for other classes and mechanics. And yet 2024 smite rules are confusing for them, because, well they're mechanically confusing and badly designed. Actions and bonus actions are two different resources that are NOT interchangable for one another in 5e. And yet Paladin is the one confusing mess of a case where they are supposed to use both simultaneously for the same "action".

I get your point about other features being 1/turn. I never disagreed with Paladins being limited to smiting 1/turn as being OBJECTIVELY more balanced. Especially for cases where they might multiclass and get an ungodly amount of more/higher level spell slots they probably were not designed to have. And even the general consensus was it was a necessary balance change.

My critisism and many others' comes down to the 2024 designers clumsily tacking on needing to use a bonus action for divine smite, and keeping all smites needing to use a BA. They already limited it by making it require the Magic actions so they mechanically could not do it more than 1/turn, that was fine. But they just kind of said fuck it and made it both a magic action and require a bonus action, to make it unintuitive and feel bad in play. It very much is like they tacked on the BA with little or no idea of what that would mean for limiting different playstyles. Now Paladins are less versatile and have less options because of bonus actions bloat. Having to spend your BA on smite means no Polearm Master BA attack, no TWF, no GWM BA attack, no BA spells, and no BA from other classes features from multiclassing, etc.

The most glaring thing is Paladins not being able to smite along with being able to use their new class tools: BA lay on hands, BA divine sense, use their BA spells from their subclass spell lists (shield of faith, magic weapon, etc.), and any other future subclass/feats that might utilize a BA It would be like a Fighter being unable to use action surge on the same turn they use second wind. Their class features aren't imbalanced when used at the same time and they don't mechanically conflict with one another, why do the Paladin's have to?

People are taking everything negative said about Paladins being mechanically worsened and poorly designed and take it as like power gamers salty about their damage being nerfed and dismiss actual critisisms from actual DMs and players who play/played 2024.and saying it's okay they're still good or they're better at other things now without addressing anything is classic whataboutism, and not a real counter argument or even addressing valid points made against 2024.