It should'n be necessary to indent email commands, it just makes it harder to use. Initially it was thought that it was a good idea to be able to interleave commands with the comments, thus the indentation was used in order to indentify commands. It's often more naturally to write commands either in the beginning of the email, or in the end, so it's better to identify commands that way, instead of relying on indentation. This also makes it easier to strip commands from emails, so that they won't show up in the description and in the added comment.
It should'n be necessary to indent email commands, it just makes it harder to use. Initially it was thought that it was a good idea to be able to interleave commands with the comments, thus the indentation was used in order to indentify commands. It's often more naturally to write commands either in the beginning of the email, or in the end, so it's better to identify commands that way, instead of relying on indentation. This also makes it easier to strip commands from emails, so that they won't show up in the description and in the added comment.