##2014
Xerath, Kassadin, Gragas, Rengar, Nidalee, Skarner, Sona, Cassiopeia, Soraka, Viktor, Sion.
All those had either a Gameplay or a Visual + Gameplay update.
##2015
Zilean, Veigar, Morgana, Ryze, Gangplank, Fiora, Poppy
All those had either a Gameplay or a Visual + Gameplay update.
Let's not forget all the Juggernaut and Marksmen update, which includes
Juggernaut: Darius, Garen, Mordekaiser, Skarner, Nasus
Marskamen: Caitlyn, Corki, Graves, Kog'Maw, Miss Fortune, Quinn, Ashe, Draven, Ezreal, Jinx, Kalista, Lucian, Sivir, Tristana, Twitch, Urgot, Varus, Vayne
##2016
Shen, Taric.
We are missing Ryze (next patch) and Yorick. Warwick comes after the Assasin update, so Warwick update will probably be live after 2016 (early 2017).
Let's not forget the Mage update, which includes
Brand, Cassiopeia, Malzahar, Vel'Koz, Vladimir, Zyra, Anivia, Annie, Fiddlesticks, Swain, Syndra, Veigar, Xerath, Ziggs
2014: 11 champions
2015: 30 champions
2016: 16 champions + Yorick and Ryze
We are still missing the Assasin update, which will probably include at least 6 champions, making it a total of 24 champions.
I would say that the reason why they don't want to give champions just a VU is because that takes times, which could be invested on another champion's VGU. Not only that, but when a GU comes along, they'll most likely always give that champion a Visual Upgrade too.
Champions Updates