Unless i am mistaken, the reason for said omission in upcoming final release was that -with- schedule and cycles included, the complexity of the game had risen exponentially, and possible main quest breaks could no longer be anticipated. In their entirety anyway. So, rather than risking people (whining) complaining about such issues left "unfixed", (read: boo hoo hoo, i killed the most central NPC and game broke, FAIL), they simply took it all out. So now eeeveryone can happily finish the quest.
I doubt that the concern was to do with the player killing someone that they shouldn't, since this can happen anyway. The problem with schedules is that - as demonstrated in Oblivion (TES4 to Morrowind's TES3), the addition of schedules can easily result in NPCs going splat without the player doing anything or even being aware of the fact that it's happening, sometimes due to unpredictable engine issues.
A famous example being the butler of Castle Skingrad who would fall to his death because, if his schedule said he should be returning to the castle as the player entered the area, he would run afoul of the fact that he loaded before the bridge he was supposed to be crossing did. Oops. ( http://www.uesp.net/wiki/Oblivion:Shum_gro-Yarug )
That's just one example. The game was riddled with issues like this that resulted from the addition of schedules and the relative complexity of the game world. Skyrim (TES5) went to a great deal of trouble to try to cut down on this, but it was still apt to happen even with the safeguards that were put in place (especially when NPCs' schedules sent them out into the wilds).
DOS isn't quite as prone to this sort of thing due to the world design, but it'd still happen, and it'd still result in a lot of unhappy customers whose games get blocked (or at least made far more difficult to complete) due to world management messes that they had nothing to do with.
Something akin to Ultima 7's schedules would be relatively safe, but still not completely so given the dynamic impact of environmental effects (something that wasn't really a factor in U7 - NPCs weren't going to randomly incinerate themselves because of the terrain unless they were specifically scripted to do so, for example).
I'd still like to see dynamic schedules added later, but only when they can be done right - and done in a way that's NPC-AI-proof.
