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Ah but there are also the hands that don't usually make game:
KQxx xx QJxx KQx
Qxxx Qx AJxx Kxx
Kxxx Qxx J9xx AQ
Considering the opening style, I think it's likely that these 12-13 counts are opening bids. Most of us don't pass the opponents 2♣ with four cards support. But the first hand we have three top minor losers and aren't that likely to get rid of all the hearts. On the second hand we lose one trick in each suit unless the spade king is singleton or doubleton onside (unlikely given the bidding). On the third hand we might make if every suit behaves but it's much less than 50-50.
It seems like an intelligent game try will get partner to accept with "pure" values (aces and kings) and pass with most quacky hands. I'm not convinced this is a case where "partner can't make the right decision" despite the fact that "not all hands with maximum values make game good, and some hands with minimum values make it excellent." If it was IMPs I would agree that just blasting the game is best, but at MPs a try seems reasonable.
I don't agree with you about hand 2. Your analysis seems to assume a diamond lead 100 % of the time after the 1D opener. On a non diamond lead, the club ace will usually be onside so you get a discard.
On hand 1 it's not so clear for the opponents to take their 4 tricks. Say you receive a heart lead and you win and lead a club up. Is it so clear for them to take the ace and cash diamonds? Maybe but it doesn't seem to happen that way in real life. What about if LHO has the AK of diamonds? He will lead a high one, and will it be clear to shift to a heart? If he plays AK A we will make. Etc. AND if we bid 3H I would not be shocked if partner tried 3N with his actual hand anyways so a game try wouldn't be much better.
Hand 3 is a terrible 12 with 6 HCP in clubs. Hand 1 has the KQ of clubs (worst cards) and QJ of diamonds for 8 wasted points. Sure, sometime game will go down if you jump to it. The relevant times are when:
1) Game goes down and pard would pass a game try.
2) Game makes and pard would reject a game try.
3) You gain a trick by concealing your heart suit and not making a game try but bidding game (most notably via a heart lead or subsequent misdefense).
In my experience concealment with a hand like this is a huge weapon. Besides I think 2 is more likely than 1 anyways (debatable).
I think the more analytical types of players downplay the gains of things like point 3 in general or of getting a bad lead. Or maybe I give it too much credit.
1NT(14-16) - 2H
2S - pass