I would't say never. Nothing is ever absolute at Riot as we constantly re-evaluate priorities and what will have the highest player value. We stopped doing pure VUs because they really didn't have much effect on the game at all for the amount of time spent on them. In fact, many players didn't even notice when we did them at all.
Lee Sin, for example, doesn't have the most up to date visuals in the game. That really doesn't prevent players from playing and enjoying Lee Sin. He is still one of our most popular champions. When we did a VU on Karthus it didn't really change player perception or engagement with Karthus either.
The gameplay updates and big VGU's have a enormous effect of players engagement and enjoyment of the game so we started to prioritize those over VUs.
That isn't to say we will never do VUs again, just that they aren't currently the highest value thing we could be doing at the moment. While VU's don't take as long as a VGU, they do take time and would slow down the cadence of our big VGUs by quite a bit. Our big VGUs have a much bigger impact and are also in much higher demand from our player base, in fact many of our players want us to do the big VGU's faster.