A brief history of the EQ Graphics Engine:
Back in 1999, EverQuest was released with a hybrid DX6/GLIDE graphics engine. This graphic engine was mainly built off the True3D engine and used sky resources found in sky.s3d.
On November 11th, 2000, the engine was revamped to use DirectX 7. The Velious only new armor textures and full screen user interface were also added at this time. (
http://www.tski.co.jp/baldio/patch/20001115.html)
On December 4th, 2001, Luclin was released. An upgraded DX8 based graphics engine named "Umbra" was included in the release. This new DX8 engine still used the old sky.s3d file and introduced new features such as back culling (via dpvs.dll), higher resolution textures, and ground foliage. Sky.s3d was updated to add the new skies for the Luclin zones. It took Verant nearly a month of daily patching to sort out the bugs and stabilize the game. Somewhere down the line, the graphics DLL was split out from EQGame.exe into it's own file, EQGfx_DX8.DLL. (
http://www.tski.co.jp/baldio/patch/20011204.html)
On July 24th, 2002, the XML/TGA based SUITE user interface system was released that enabled the bazaar zone and user interface customization. The SUITE user interface also killed/abandoned the old in-game bulletin board system. The SUITE user interface eventually became mandatory on January 9th, 2003. A couple of new skies were added to sky.s3d for the Planes of Power release. Around the time of Lost Dungeon's release, the ability to specify NPC model loads using zone "_chr.txt" files was added. (
http://www.tski.co.jp/baldio/patch/20020724.html and
http://www.tski.co.jp/baldio/patch/20030109.html)
On March 23rd, 2004, Sony Online released the 3rd generation EverQuest engine that required DX9, called "EQGraphics". This engine was contained in a new graphics DLL file, "EQGraphicsDX9.dll". Unlike the first and second generation engines, the EQGraphics engine revamped most of the major data structures behind EverQuest. Sky support no longer used sky.s3d and instead drew all its data from the newly formed "Resources" directory. The default engine graphics format changed from "BMP" to "DDS". A new zone resources format called "EQG"/"ZON" was created for newer zones. "S3D" compatibility was maintained for legacy purposes. The entire collision system was revamped at this time, causing months of collision related issues. Collision related patches went on for months. Boats were the most severely impacted item. The boat system was non functional for several years after the March 23rd patch. To this day, there are still boat collision problems that originated from the original March 23rd patch. (
http://www.tski.co.jp/baldio/patch/20040323.html)
Where Titanium and Project 1999 Fit In:
Project 1999 is based off the EverQuest Titanium box set. This box set is the earliest box set supported by the EQEmulator base project. The Titanium box set was released on January 11th, 2006 and contains an EQGame.exe dated November 8th, 2005. This release was made during the modern "3rd generation" era and therefore uses the new "resources directory" sky format mentioned above. There is no way to load the old sky.s3d into the 3rd generation graphics engine without manually upgrading the resources from the old file. (
http://www.tski.co.jp/baldio/patch/20051027.html)
That is the long answer to why the old sky system will not be coming back.