It's quite natural considering they need a striker now because some of their strikers can't back up when Benzema isn't playing or not doing well
If only to be used as a cover for Benzema, Lewandowski would not want to wear the Real Madrid uniform, because Lewandowski's standards are not as a bench warmer. Real Madrid and Barcelona have shown interest in signing Lewandowski, if Real Madrid cannot guarantee Lewandowski is in the main squad, he will choose Barcelona as his new club.
Maybe Lewandowski would prefer to join Barcelona over Real Maddrid if Bayer Munich let him go and I think Lewandowski also realizes that if he joins Real Maddrid, his career will be dimmed because it doesn't look like Ancelotti will play Lewandowski fully in the game, but if he joins Barca it's a possibility. Lewandowski will always be used by Xavi because the Barcelona team is currently looking for a better striker than Luuk de Jong and Martin Braithwaite for next season.