In my opinion, King's Quest V is a 100% Roberta game
KQV was 100% Roberta, and she was the one who wrote the story. (that's not diminish the involvement of capable artists, programmers, and musicians). The other two credits listed above are company wide credits, and not KQ5 specific.
Ken Williams and Bill Davis had little to do with actual game development back then, they were tossed into the credits due to their positions in the company.
Skirvin was behind the art direction as far as I know.
Actually the reason why Roberta had little involvement with the KQ1 remake, was because she was busy working on KQ5 at the time.
I'd like to show you guys a recent Jane Jensen interview where she talks about how Roberta really made all the big decisions regarding King's Quest VI. She says something to the order of (and I'm paraphrasing here), "Roberta called all the shots, and damn it, she was usually right." I'll keep searching for the interview on my spare time and post it here if I find it.
As I understand it, Roberta was very much focused on the direction o the technical & visual aspects of the game. She collaborated with Jensen on basic ideas for plot (she may have even suggested which fairy tales/mythology to include). Actually in general Roberta's role in later games was more about technical/innovations than the game plot. She used her games to push the technology in new directions.
She just didn't have much involvement in the actual story writing.
It's stated in the KQ6 Hintbook that Jane Jensen wrote the entire story while Roberta Williams was away in Europe. So there is little evidence that Roberta had the chance to read over the entire script (which would explain her lack of knowledge of the Black Cloak Society). The idea is a minute reference near the end of the game (which might also explain why it was overlooked).
Roberta even said during an interview;
This quest seems to have a darker, more ominous tone than the other King’s Quests; it is also more wordy. Is there a reason?
I was thinking that same thing the other day, but I don’t believe we made it intentionally ominous. It just turned out that way.
The reason it’s more wordy is that I didn’t write the text. This is the first time I have had a collaborator. Jane Jensen wrote all the script, and we worked on the story line and character together. We spent a month working together before Ken and I left on a two-month vacation to France.
Jane has a different style than I do, and maybe she is more text oriented. Even her design documents were four times as thick as mine usually are - her fingers just fly on a word processor.
With MOE, she went back to writing the story (and was also very much involved with the character casting). She was still trying to innovate the technology and visuals at same time.
However, not all the technology innovations in the game were purely her ideas, many came from other members of the staff. The idea for combat was apparently suggested by Mark Seibert originally. Apparently early on, Roberta had the idea for the large empty world map, and there was nothing to do between puzzles, just pure exploration in large empty spaces. Mark thought it was too empty, so he suggested the idea of adding enemies (along with that the weapons, armor, and potions) to those spaces to keep players occupied between puzzles. Roberta initially argued against it, but was convinced it was a good idea (actually it probably was a better idea and improvement to her initial 'empty spaces' exploration direction). Considering that some people still complain that those spaces are "too empty" even with enemies. Seriously, imagine what it would have been like with 'nothing'.
Consider that even her early prototype ideas with the "statue" had most of the citizens of Daventry turned to stone... Having few 'living' characters to interact with, and no combat would have made the game (especially Daventry) extremely bleak (more so than it currently is in the game)... I don't know, in this case, if Roberta had stuck to her original vision, it might have made things worse...
Her own son suggested the ideas for box puzzles, and platforming/platform puzzles originated from playing N64 games like Mario 64 and Zelda, that Chris played. But who introduced those ideas to her initially is unknown? Could her own son have influenced aspects of the game as well (that were not purely Roberta)? I have to say, as far as puzzles are concerned, those are some of the least compelling in the game.
Seriously, if what Ken said is true, and its the fact that combat was added to the game, was one of the things that Roberta questioned (at least initially), but added by Mark Seibert anyways... Then I can't say her original idea was any better!
I know a few other ideas were cut more to do with limitations in the technology, and due to screwups by Dynamix's development of the initial game engine. One level for example mentioned in the Talk Spot interviews was to be set underwater, but they couldn't get the swimming or water currents to work properly. So it had to be cut.
Some of the more elaborate scripted events such as the sequence with the witch, was cut because the final game engine couldn't handle anything more elaborate, or the sequence was incomplete. There were also a few bosses that were cut due to time constraints (but then again, for people who don't like the combat, less combat is better?). In some cases bosses were replaced with another boss that better fit the surrounding enemies (as the previous ideas were out of place and had no explanation in the game), I.E, the spriggan boss in the castle ruins replaced a leprechaun/red-capped goblin (see making of video).