I think @Scimonster is misunderstanding. Shulchan Aruk Ha Rav (SAHR) 190/5 says you have to drink from the cup of blessing:
שולחן ערוך הרב אורח חיים סימן קצ סעיף ה
...אף על פי שמצוה מן המובחר שכל המסובים יטעמו מכוס של ברכה
And later ibid he says that if you are not drinking from the main cup, and you have your own cup in front of you - These cups become a cup of blessing and as if you are making kiddush on your own cup through hearing the main recititation.
הרי כולם הן כוסות של ברכה כמו כוס המברך
Now his quoted Shulchan Aruch, Orach Chaim (SAOC) 271:14 - does not give a reason to why they should taste, or what they should taste. You can say SAHR is explaining or arguing. If he is arguing, then drinking any wine should suffice. But that is hard to back up. In SAOC 190:4 in talking of the cup after grace, he uses the same language - best if everyone tastes
שולחן ערוך אורח חיים הלכות בציעת הפת, סעודה, וברכת המזון סימן קצ
מ"מ מצוה מן המובחר שיטעמו כולם ....
Now we do not see anywhere that everyone drinks their own cup of wine after grace, but only from the cup of blessing. It would infer that when the SA talks about a cup of blessing, & says all should taste - it would mean specifically from a cup of blessing.
The Mishna Berura (MB)(174/3)says anyone who does not drink from the cup of blessing for kiddush needs to make a blessing on his drinks for the meal.
משנה ברורה סימן קעד ס"ק ג
ודע שאם קידש על היין והוציא אחרים בברכתו
אם לא טעמו מכוס של קידוש ורוצים לשתות שארי משקין אף שהיו לפניהם בשעה
שבירך על היין צריכים לברך על המשקין
Why does the MB go out of his way to say drink from the cup of blessing when he could just say drink, if the rule for kiddush is just to drink. Rather the drinking of everyone is to be from the cup of blessing.
The main reason for all to drink the wine is to partake of the cup of blessing. This would lead to being no point of drinking when not the cup of blessing. However you can turn your cup in front of you into a cup of blessing. The problem with this is you need all the things that a blessing cup needs. Full, not pagom etc. But most importantly the cup needs to hold a reviit which is 85ml min. Not a shot glass of wine. If all is good your blessing on the wine is covered by the kiddush that takes affect on your cup.
There is another reason that people would drink wine, unrelated to the cup of blessing, is because of their love of the mitzva of kiddush they want to drink wine even if they cant have from the cup of blessing. If this is true then there is reason to drink even if not from the cup. But I have not seen a source for this, and I find it difficult to say that is what the SA means, as per my points above. Also if this is the reason I think that a blessing should be said on the wine, as we do not say blessings of food for other people today. That is a point for another thread. (Kiddush and Bread which we do say for others is on the mitzva not the food.)
There is no kidush text per say for Saturday, just the blessing on the wine. So its easier to say it is a bracha on the wine rather than the mitzva so could cover the shot glass of grape juice. But the Brisker Rav learns from the GRAs proof from Pesachim 106a that Saturday kiddush is also a bracha on the mitzva not on the wine. If true there would be no difference between Friday and Saturday, as indeed the Gra learns from Saturday kiddush to Friday kiddush that you have to drink from the cup.
I am writing this as I want to be challenged. And if you do not like anything I am saying I would love to have it pointed out with sources - would be much appreciated.
EDIT - another Source
The shut Zevchai Ztedek, Orach Chayim 27 - explains the SA that everyone should taste as only referring to when they have their own cup, but there is no need to drink from the main kiddush cup
שו"ת זבחי צדק חלק אורח חיים סימן כז
הרי בהדיא שדין זה שכתב מרן דמצוה מן המובחר שיטעמו כולם הוא מקורו מן
הרא"ש ז"ל והרא"ש ז"ל בהדיא כתב שיש לכל א' וא' כוס בידו
However if there is only the one kiddush cup then because of a love for the mitzvah you drink from it.
דצריך לשתות מכוס המברך אפי' אחר ששתה הוא ממנו משום חבוב מצוה
So at least it is a source to drink for the love of the mitzvah - but still it is from the cup of blessing!