We’re afraid to give instructions. Despite imperatives being the fastest and most direct way of giving someone instructions, they remain unpopular.
Can you imagine writing “dogs are advised that they should sit down”? Of course not. “Sit” suffices. So, rather than saying “I should be grateful if you would please send it to me” just say “please send it to me.”
This fear of commands probably comes from a fear of sounding rude. Just put please in front of your words and it will sound polite.