Craftworlds have not been dropped.
They were solely background entries in White Dwarf 127, and the second edition Eldar codex, the original third edition Eldar codex, and the current Eldar codex, so it is codex Craftworld Eldar which stands out as being an anomaly for forcing people to field the big five craftworlds within too narrow a force organisation chart.
I would like more players to build armies which take account of background, but presenting them with straight jacket options which also ran contrary to Eldar background in earlier and later books was not the way to go about doing it, so I think GW did the only that they could do to fix the system at that time, and that was to scrap it completely.
I'm sorry to disagree with you Irisado, but I find the 4th ed Codex coupled with 5th ed missions to be the biggest straight jacket for Eldar.
1st Ed Eldar, WD 127, didn't limit me to which Aspects Warriors and guardians I could or could not choose. The force org on page 31 is very open and lenient. The only restriction was on jetbikes, but even GW back then knew and admitted to future jetbike armies. Page 39.
2nd Ed Eldar was percentage based force orgs. And all the Aspect Warriors were still basic squads , "troops". Jetbikes, Scouts, Wraithguard, and other units joined in the fray as well, adding variety.
3rd Ed 40k brought in the fixed force org tree we have to this day. And only rangers, guardians, and Dire Avengers now counted as troops. This was somewhat ok, because the 3rd and 4th ed 40k ruleset was still "kill em all and let's count the victory points" and there were no broad restrictions as to whom could count as a scoring unit.
The 3rd ed Craftworld Codex came out to give more variety to what force org builds can be used. Not as broad as 1st or 2nd ed nor perfectly balanced, but hey, something better than nothing. And the EOT USF force org was interesting, if not abused.
The combo of the 4th ed Codex and 5th ed rules and missions really killed force orgs, composition, and flexibility. The Craftworld force orgs were effectively gone. Randomly 2/3 of all missions count on Troop choices to get the job done by taking objectives. So even if I wanted to spam Aspect Warriors with the current force org, I'd be shooting myself in the foot if my one scoring aspect warrior unit option, Dire Avengers, aren't in the right place (blasted random objective point) at the right time (blasted random game length)
4th ed Guardians have the least amount of unit options out of all the editions. Counting on them to carry the game, take objectives, and not sacrifice kill points, is a long stretch. Granted, guardians never were rock and roll butt kickers, but now they really hurt.
So what do I see? Fast mechanized armies that can meet the demands of random mission objectives and scenarios and random deployment zones with a clear mind on keeping troops alive and inflicting pinpoint damage on single enemy units, not all-in total annihilation or sacrifice units to deny annihilation. No sacrifice guardians in 5th ed. No extraneous units that can neither take an objective or annihilate a single opposing unit to the man or provide the speed
and resilience to contest a single objective at close quarters.
Hence Eldrad, DAVU Waveserpents and Falcons, Mechanized Fire Dragons, and Fire Prism.
Eldrad to handle random deployment zones and provide buffs.
DAVU Waveserpent and Falcons to take objectives at maximum point efficiency and speed.
Mechanized Fire Dragons and Fire Prisms to maximize pinpoint damage on single units, taking a kill point or eliminating an opposing unit whenever the opportunity arises.
Boring, boring, boring.