What does each side want and how do we give it to them?
The Sliding Scale of Meaning vs. Balance
I think the question you missed is why can't you have PC death on the line every combat? Shouldn't that be a significant point of combat?
That's one of the reasons I like 4e. In earlier editions, I often had to hold back or "play dumb" in order to avoid an excessively rotating cast of player characters. In 4e, I can go all out and be assured that although the players may feel hard pressed, I'm not going to make the death rate skyrocket. PCs still die in our games, just not every session. Having PC death a reality in every encounter is not the same thing to me as, say, PCs only having a 50% chance of surviving any given encounter. Since PCs can be expected to fight dozens, or even hundreds, of encounters during their adventuring careers, even a relatively low chance of death can (and most likely will) result in deaths.
I may be completely wrong about this, but I think Harlem Globetrotters CaS falls somewhere between a myth and an uncommon play style. I don't really see why it would appeal to anyone. If you know you're going to win, why not just skip the combat (or narrate your victory)? In our games, virtually every encounter has the potential for character death.
I also think it's mistaken to say that you can't have encounter balance with a sequence of encounters. I agree if what you meant to say is that you can't ever perfectly
create balance in a sequence, but since my first few 4e sessions I've been pretty good at creating a sequence of challenging encounters that have a high chance of leaving the party with only a few surges and no dailies, but doesn't result in a TPK. The fact that I attain such results with regularity indicates to me that the balance is pretty good.
I think a major factor in 4e in having fairly steady encounter balance is that significantly less resources are tied to the adventure day, but rather the encounter.
In earlier editions, almost everything was effectively a daily resource. Sure, the fighter could attack at will, but his hp were tied to the cleric, who was in turn tied to a daily healing resource (let's ignore wands of CLW for now, as limit circumventing magic items are tangential to this discussion). A fighter without hp couldn't attack, after all, and a fighter at low hp would be reluctant to. Thieves could find traps at will, but were similarly limited by hp. Wizards were also tied to daily spells.
4e changed this, by tying things more closely to the encounter level. As we've seen from the Essentials classes, dailies are hardly necessary for the classes to work. However, we have yet to see a 4e class without at-will and encounter powers. Even healing surges, which are technically daily in nature, exist in sufficient quantities that the likelihood of expending them all in a single encounter is virtually nonexistent, and rather than everyone being dependent on the cleric's limited pool of spells for hp, every character comes with their own pool of surges. As a result, the outcome of a sequence of encounters can be predicted with a high degree of reliability.
Now, admittedly, if you return to the earlier method of balancing along the adventure day, attrition is the way to go.
However, things become far less predictable, so it's a pretty heavy trade-off. It also excludes certain play styles completely (low combat campaigns, where attrition is not a factor because you'll almost never see more than one combat per day). 4e doesn't do the one combat perfectly (due to the possibility of daily nova) but I think it could. It should be possible to create a chart that indicates how much you should increase the xp value of an encounter to account for it being the only one the PCs will see that day. I've eyeballed such encounters with good success.
I even think you could achieve an encounter balanced design that still allows vancian wizards. They would need less (daily) spells though. Let's assume that 5e baseline is that there are 4 encounters per day, each lasting 5 rounds, and that a wizard should cast 2 daily spells in a typical encounter (the rest of the time he uses at-will feats, because spell conservation is an important aspect of the vancian mage). Therefore, a wizard gets 8 spell slots. Since an encounter is expected to last 5 rounds, WotC can estimate the number of extra enemies you should add to an encounter where a wizard casts 5 spells, in order to get that combat to last 5 rounds. Give the DM that chart, and he suddenly knows what to do if he only wants to run a single encounter, despite daily resources in the mix.
I do think, however, that healing surges (or something like them) are a necessity. Otherwise, hp recovery becomes reliant on the cleric's limited resources again, and that will create vast descrepancies in party potency. A party of 3 fighters and 1 cleric will have far less lasting power than a party of 2 fighters and 2 clerics, and any ability to predict outcomes goes right out the window.
I agree that minimizing things that aid in the 15 MWD is a good way to go, regardless of which play style you prefer.
Just to point out an alternative (though one that would be highly unpopular), you could completely eliminate the 15 MWD by eliminating all daily resources. If all of the party's resources are AW/E, then they have absolutely no incentive to rest. I do realize that this extreme isn't really desirable though.
I think it's important to note for this discussion, however, that the 15MWD arises from attrition. Eliminate attrition and you eliminate any reason to rest (again, not something that's entirely desirable).
The Glory of Tactical Play
Tactical play will always take longer than non-tactical play, IMO. Just make it modular (preferably so that I can run one fight non-tactically and the next tactically) and the DM can decide what is most appropriate.
It would be a little amusing if the length of CaS-style tactical combats was there to encourage CaW-style strategic play. Don't like the length of combat in 5e? Figure out a way to drop a flaming hut on your enemies, and you won't have to play though that lengthy combat!
The Glory of Strategic Play
I’d like to see this kind of spell be the core of the 5ed Wizard class and have the Wizard be relatively weak at straight-up combat in order to compensate for its strategic utility (with more blasty casters being possible, just not the Wizard default).
I really don't like this idea. Firstly, it marginalizes the Wizard for CaS style play. Secondly, it reinforces the stereotype that CaW players use spells as a crutch, and that casters are the only thing worth playing in a CaW style game. It's not that I'm against the idea of using spells for CaW. However, I don't think that magic should win the CaW "Most Valuable Resource" award, despite that it traditionally has. I think you can encourage player creativity far more if there isn't a go-to magical solution for everything and anything.
Personally, I much prefer encounter-based balance to any other variety. That's not to say that there isn't room for one class to be superior in a given encounter (though I don't think any individual class should be superior for a majority of encounters) but I really enjoy the predictability that encounter balance provides. I like being able to challenge my players without having a supposedly CR 7 creature kill the level 6 psychic warrior in a single round.
While I don't think encounter balance is inimical to CaW players, I find that those who prefer CaW don't seem to like encounter balance. It might be because it reduces the amount of swing present in the game, and CaW players seem to prefer the game swingy. If that is the case, it might be possible to preserve encounter balance in CaW style play by simply offering some swingy options for CaW players. Of course, that's not to say that CaW players should put a Level 5 Dragon in lieu of an Ancient Dragon just because the party is level 5, but rather that the DM would understand just how much that Ancient outclasses the party by (until they come up with a clever strategem to eliminate its advantages).
Perhaps a bit rambling, but those are my thoughts on the matter.