Because you get trapped like this: PS WSOP Double Shootout. Calling at the end is a must since the potential existed for a busted flush draw:
PokerStars No-Limit Hold'em Tourney, Big Blind is t20 (9 handed)
FTR converter on zerodivide.cx
MP2 (t1750)
MP3 (t1430)
CO (t1510)
Button (t1305)
Hero (t1540)
BB (t1915)
UTG (t1470)
UTG+1 (t1300)
MP1 (t1280)
Preflop: Hero is SB with A[img]/images/graemlins/club.gif[/img], J[img]/images/graemlins/heart.gif[/img].
<font color="#666666">
1 fold</font>, <font color="#CC3333">UTG+1 raises to t60</font>, MP1 calls t60, <font color="#666666">
4 folds</font>, Hero calls t50, BB calls t40.
Flop: (t240) 4[img]/images/graemlins/diamond.gif[/img], J[img]/images/graemlins/diamond.gif[/img], 4[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">Hero bets t160</font>, BB folds, UTG+1 calls t160, MP1 folds.
Turn: (t560) 9[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets t300</font>, UTG+1 calls t300.
River: (t1160) 8[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, <font color="#CC3333">UTG+1 bets t300</font>, Hero calls t300.
Final Pot: t1760
Results in white below: <font color="#FFFFFF">
Hero has Ac Jh (two pair, jacks and fours).
UTG+1 has Ah Ad (two pair, aces and fours).
Outcome: UTG+1 wins t1760. </font>