A Tough Decision?

K Q J
Q 8 7 3
A K 10 4
10 4
10 5 8 4 2
9 6 5 4
9 8 7 2 Q 3
K Q 9 8 7 3 A J 6 5 2
A 9 7 6 3
A K J 10 2
J 6 5
------ Opening Lead: K of clubs

SouthWestNorthEast
1 Pass 2 Pass
2 Pass 4 All pass
How does anyone look at 3 spades and 4 hearts and say,"Pd, I prefer spades?" Does this betray a misunderstanding about the value of the balanced fit over the unbalanced? After all, South may have only 4 hearts on that bidding. Or did he fall in love with three lovely spade honors, as opposed to only one honor in hearts? Can't say, though one might point out to such a mentality that declarer will surely make use of those top spades in a heart contract, and conversely, if there are holes in a 4-4 heart fit, they'll still be there in a spade contract.
Anyway, you will note that in a heart contract, grand slam is a laydown (or an overtrick in little slam), while in a spade contract, you'll very likely be held to 12 tricks -- unless one is adept at dropping doubleton Queens with six cards outstanding, which this declarer wasn't. The unbalanced spades allow two sluffs in dummy's diamonds in a heart contract, while in a spade contract, you sluff only one diamond on the 5-4 hearts and are still beholden to an unlikely guess to pick up that 13th trick.
I cannot forbear relating my own experience with the same two suits but different circumstances. It was an Individual tournament in Boston, a two-day, four-session event, and barring a few exceptions, you've never seen your partner before and so keep to pretty tried-and-true conventions. I opened a no trump with -- as it turned out -- the misfortune to hold 4 cards in each major. Two clubs by my partner. Two spades by me. Three no by partner. Four hearts by me. And as soon as my partner's brow crinkled, I said "Oh-oh. I'm in trouble". I mean, what is there to think about? But sure enough, my partner with three spades and four hearts took me back to spades.
I'll never understand that one. He's looking at three spades and four hearts and says, Pd, I prefer spades. Yes, I know: I shoulda said 2 hearts with both majors. . yes, yes. I figured that out.