Anivia AA range
Simply put. Why does Anivia have 600 auto attack range? She out ranges most ad carries, can harass down any mele champs in lane without having to expend any effort. Even ranged champs like ahri or veigar have to suffer some degree of harass without being able to fight back as if they get closer the entire minion wave will jump their ass. Its not like she suffers in waveclear, post 6 she just drops R and walks to the edge of the range, ensuring you cant harass her while she clears the entire wave. Dont get me wrong, Anivia is a good champ. She is great vs heavy push teams as she can obliterate the wave from a distance compleatly countering these team comps. Can we make her have to take a few more risks in lane.
Remember when annie had 600 AA range and was one of the most popular supports just because she didnt even have to expend mana to harass the living hell out of the enemy botlane? well this is somewhat of the same thing.
here is a list of marksman she outranges
(without ult)
(if he still counts as a marksman)
(no w)
(for a while)
(without q) 
Can we tone it down a little? 600 AA range is huge and it isnt required by her theme.