Why do some 360 pages allow you to write on their page whereas with others, you can only send a smiley?

Question

Regardless of whether I've added them as friends or not

Answer 1

can not say any better than above it is the settings the holder of the page has put them on, you have set yours to just leaving a smilly and so on with no comment by public, those not on your friends list.  :-( lol

Answer 2

They control who can post comments and who can't - say if they only wanted to allow their friends to comment they can set it to that. It says 'setting' just above the comment box. And they have to accept your invitation first, before you can comment them. If they don't want anyone to comment their page they can set it to 'private' which doesn't allow anybody, including friends to comment =)

Answer 3

The person who controls the userpage has chosen to prevent people from leaving comments, even their friends.