It's a small change that makes the overall look more buttoned up and refined. With Sampere she's walking, not posing, but sense of movement aside the...
Or Peter died and was replaced (temporarily) by Doc Ock, or Mephisto dissolved the Spider-Marriage, or Aunt May's death in #400 (also temporary), or,...
I can safely assume you've never read "God Loves, Man Kills", "Kraven's Last Hunt", "The Killing Joke", "All-Star Superman", "Superior Spider-Man" or...