Because one of Peanuts running gags is Charlie Brown being hopelessly in love with the Little Red-Haired Girl, but never working up the courage to talk to her. The Peanuts media generally operates under a very strict set of rules when it comes to their stories, and CB being too scared to talk to TLRHG is one of those rules.
Are you against Pokeshipping too? Do you ship SatoGoh and Serena and Lisia or Serena and Chloe or Serena and May?