ZPavelZ: Now, first of all, thanks for creating the puzzle and congratulations to the winner.
Normally I would bow out with this phrase but seeing the comments of the author of this thread I would like to give some feedback that might help him with the future puzzles.
1. Analogy. Your puzzle was basically a "solve this by analogy" type of thing. This means that basing on the way you paraphrased something others should guess what you had in mind. While it is an interesting concept and you worked well on it, there are certainly some things missing.
The answer was: A solution to a problem is a necessity, But a solution is useless if it isn't functional.
The paraphrase was: A door to a house is vital, however, if one does not build stairs then the door is pointless. In order for the door to be useful, stairs must follow.
While it is a nice way of re-saying the clue it is not 100% accurate. First of all, when reading the paraphrase one would certainly concern "house" as something that integrates ("includes") the two other thing - "stairs" and "door" (it is not obvious at all the stairs were supposed to be outside not inside - not a single person itt except the author understood that).
Now as you all know the problem does NOT include the solution, because if it would than there would be no problems with that problem. :P And surely the problem itself does not care whether it has a solution or not. It is necessary for those WHO solve to solve the problem.
I read the paraphrase as "there is a whole, which includes two consecutive things, each of which is included into it". Thus I no way could decipher the message based on the paraphrase.
Again obviously the word "functional" is not consecutive to the "solution" - "taking actions based on the solution" is, however.
The way I would re-do this puzzle off the top of my head would be this:
Solution: It is vitally important to solve the problem. But solving a problem is useless unless actions are taken based on that solution.
Paraphrase: Finding a key to the chest is utterly important. But the key is useless if one doesn't use it for unlocking.
I know this is VERY obvious, but I just give it as an example of how such thing could be done.
What we had, however, was both very general and not very accurate thus leaving people roam in all possible directions ( I was not the one, who posted about sex, but I 100% agree with that person).

All the abovementioned, however, would be a non-isse if there would be good CLUES.

2. Clues. Now, I definitely have to say the clues were not helpful in any way to the contestors.
"Someone was on the right track" - yeah there were 20 people, each going in different direction and so any one could be right. Does nothing.
Mixture of two substances - who said it is one word? Milk+coffee - two substances and they mix. Again not really something you could start your logical thinking from.
Those were the only two clues that I saw before the final derby started (I was asleep at that moment so I didn't even see it). There were other posts by the author, but I personally didn't see clues in those.
Now, what I would suggest instead would be giving clues concerning general puzzle meaning instead of separate words.
E.g. - this puzzle is NOT about physical particular objects (this still leaves a WIDE field for guessing, but at least no one would have ot repeat "teeth-stomach" combination 3 times).

If you have doubts about it here are some possible guesses (non-particular physical objects):
Requirements to desing are essential, they are useless, however, unless serve as basis for a design concept.
Terms for a theory are essential, they are useless, however, unless they are used to formulate logical implications used in turn to describe something.
....
I could do this all day.

Anyway, thanks again for being so generous and entertaining people on the GOG forum, and I hope what I wrote doesn't sound rude - I didn't mean it that way. Hopefully, it would also help everyone in the future!
Cheers!

Nroug7: Oh, i assure you, none of that was done by accident, it was all very deliberate, however i am looking into making the next one an easier process.

ZPavelZ: So the non-accurate analogy and non-logics-inducing hints were made on purpose? Ok, I am sorry than to have meddled into your puzzle creation process. Obviously, I was unaware this was the way it was deliberately designed. Thanks once again and all the best.

Nroug7: No, i meant it was deliberately open-ended. and i didn't mean it in a sarcastic or harmful way so i am sorry if you took offense to it (which i think you did to give me such a sarcastic sounding response.) of course i also left my clues open ended.

ZPavelZ: Ok I am sorry too than, if what I wrote sounds insulting to you. Obviously there was some misunderstanding. What I was trying to say with my initial post is "even if you made your puzzle a bit more particular there would still be lots of open-endedness but that would also make it more solvable - without you literally telling people what the first, second word is and so on". On the other hand I DO realize you might have other things in mind and I can only propose something while in the end what to do is always your choice as it is your puzzle definitely. :)
If I speak about personal preferences I would definitely like more particularity as I was 100% lost to the end of the puzzle and I literally had nothing left to say. But than - may be that is what other people like and want to see in a puzzle? So, hey, why not! :)
To be absolutely frank I do feel a little upset by the way things turned out to be - I put some effort into solving this puzzle (well others did as well) and in the end it just came down to "hey here's what's the first word guess what's the rest" kind of thing. On the other hand, English is not my native language - I would not even dare (yet) to make such a puzzle myself as it might be too broken for people to solve, I am new to GOG, I was warmly welcomed here so I really am not in a position to complain. I just thought I might give some comment you might find useful, that is it. I understand my advice might be totally useless also, depending on what you have in mind. That is why I did not want to seem overwhelming (which I am afraid now I already do :( ).
P.S. Also I wanted to point out there was an obvious logical "error" in the way the puzzle was paraphrased and you saying it was deliberate made me just go =/ Again an obvious problem on my side as a someone, for whom English is not a native language. I am sorry for that.