If you take a look at the Sabella's team you see the core is mostly made of the players who are almost all of the same age. Most of them been playing together since U-19 up to now. Bringing Willy in who has "never" been in the NT, right before the main event, may cause more damage than good to what Sabella has tried to make over the years with his team. Willy might feel like an outsider among the players who know each other for years. He got to know a defence that he has never trained or played with in such a very short time, which is nearly impossible now that we're only months away from the WC.
Intl football is all about fine margins. One poor decision, can prove fatal to the team's chances of progressing. Having no worthwhile competition in the squad, only breeds complacency, and its exactly why Romero's performances have gone south (+his no-show at the club level). He knows regardless of his club situation, and NT performances, he can always walk straight in to the XI. Keeping the self-serving Tevez out makes sense, as this Arg is messi's Arg. But Romero is not indispensable to this team. Willy and Romero should co-exist for the greater good of the team. If Romero doesn't like it, too bad, he can stay back at Monaco waiting for his next paycheck. Its not like he'll be missed much.
As for the highlighted part, like romero knows?
The fact that he's hasty to come off his lines, even when his defence is there to cover for him suggest, despite the familiarity in the dressing room, there is no reliable communication between them on-pitch. His positioning is poor in general, and so are his reflexes, and ball distribution (something even Andujar is better at). Having an odd good game here and there isn't the hallmark of good goalkeeping, but consistency is. And Romero is far from a consistent one. Willy, unlike Romero, is more of a leader, and commands his area better. His body of work has earned him respect and praise, even by some of the current Arg members. I have no reason to believe he won't be well received by the squad, or that he'll create dressing room prob. The man is a pro through and through. His potent fundamentals will facilitate his settling period. And the defense will be better off knowing they 've a reliable keeper at the back.
As for the class of 87/88 argument. Sabella has had no qualms about calling up the likes of Braña, Somoza, Guiñazú, Ponzio etc. Most of them in decline, and unfamiliar to the "current young rockstars". Yet, Sabella didn't feel the need to acknowledge the best Arg has between the sticks. If excellence is not rewarded, you're setting a bad precedent to the others, and if sabella can't find a place for willy in his squad to Brazil, he is morally and practically wrong. Any excuse against his inclusion at this moment is just lame. End of.