I disagree on both points.
A half-caster isn't the solution. A half-caster would just be another missing of the mark. People who want to play a Swordmage or the like, don't just want basically a Paladin/Ranger but with Arcane spells, and INT-based AC or something. They want split into two groups, in fact, I'd say:
1) People who want an Arcane-magic-THEMED melee, but who don't give a toss about actual spells, and indeed might well dislike them. Half-caster is not a solution any more than EK was there, it's just another annoying missing of the point. This is a huge group, frankly.
2) People who want serious magical punch but also want to be flouncing around with a sword and in light or no armour. This is already solved via Bladesingers and two flavours of Bard (though exactly which two I leave to your discussion).
If we go half-caster, we just make the same dim mistake as PF1E, which had as noted by others, a bazillion of these, all of which were mechanically complex, poorly balance, and worst of all, not actually fun to play, because they didn't really express the fantasy of the "magical warrior", because they were so bloody finickity. 4E OTOH managed to nail the concept repeatedly.
And WotC don't often miss the mark here (unless you're meaning very specifically with this one archetype). They do sometimes - c.f. the Sorcerer, which exists purely to express a mechanical approach, and which nearly gained an actual identity in the DNDNext playtest, but they chickened out. If they often missed the mark we'd be flooded with dubious classes which exist more for mechanical reasons. The last time that was close to true was 3.5E, but even then most of the new classes (excluding PrCs, which were 95% trash) justified their own existence by more than "here's some mechanics!".
The only argument I can see that they did "miss the mark" is re: Type 1 - D&D is missing that, and it would be popular. But Pathfinder 1E-esque half-caster melee? Ugh. Fail, imho.