Because Cavani is apparently their no.1 target along with Bale. With Ronaldo probably staying and Cavani already confirming to his family that Real is his preferred destination, there'll be no place for Suarez there. Unless Bale stays at Spurs.
Higuain is definitely leaving, and there's a reasonable chance that Di Maria is also on his way out. Benzema has been inconsistent(and has legal troubles), and Callejon is also likely departing. If anything, I see a potential glut in the midfield moreso than in the strikeforce.
Cavani
Bale
Ronaldo
Benzema
Madrid are going to need another attacker to complement that group, because no matter how talented they are, there is virtually no cover. Either way, can't see that being the deciding factor in if they sign, or don't sign Suarez.