Overall, I like the focus on "gameplay", that seems to influence all design decisions and every specific interesting aspect. How does a mechanic actually work at the table, during play?
I think for example Healing Surge and the way they are used come from observing how earlier edition hit points worked. Once you had 3.5 Wands of Cure Light Wound available, it lead to a particular effect at the table - hit points were no longer a daily (or even longer) resource to use. It's a resource used per encounter. The longer-lasting resource were the number of Wands (or charges) the party had at its disposal. If you used standard wealth guidelines and access to item creation or magic item shops, the Wands would almost never run out at some point.
But these Wands were pretty much useless in combat. A healing wand gives you a lot bang for your buck if your buck is measured in gold pieces, it doesn't if it is measured in standard actions. The out-of-combat economy is not the same as the in-combat economy. From a playstyle perspective, this often meant that only Mass Cure Spells and even better Heal spells were really useful to the party, but most of the time offensive uses of your actions were even better.
There would have been different ways to deal with it - they could have removed the healing Wands out of the game, for example, and keep the hit points how they used to be. But they found that having a more or less reliable number of hit points in every combat encounter to be useful for balancing combat encounters, increasing predictability. On the other hand, without any slowly regenerating resources, you basically force every combat encounter to have the same difficulty - there are no long-term consequences to worry about. Such a system would certainly work, but it lacks a dimension of complexity and a way to challenge the players.
So Healing Surges provide the slowly regenerating resource, any "triggers" (like Second Wind, Bastion of Health, Inspiring Word or Potions of Vitality) are the encounter resource you don't want to run out. if a combat doesn't cost you all your encounter powers, it can contribute to the challenge over the adventuring day - because while you might get your triggers back, you don't get your surges back.
This is just looking at the isolated element of healing - the at-will/encounter/daily power resource system adds to that, with similar observations.
So I think what 4E does right, overall, is "understanding" the game. Not everyone likes the results. But that is not because the designers didn't know what they were doing, but they were designing their game for particular purposes. There is a reason for each game element to exist, and it is not just because it makes "sense" from the world perspective or makes for a good story, but because it achieves a certain goal for the gameplay.
It's still easily possible for someone to dislike such a game. If you don't like resource management, any clever attempt to create a resource management system is still a clever attempt to do something you don't like.
