What happened to transparent tiles?

I've got the transparent tiles and they look good. Best to set the tile colour to something like the grey-ish one, they become more transparent then.

There is already the concept of transparent tiles implemented by the Xbox One. It may not be what you envisioned and you may have better suggestion for future updates to this feature. Head over to the Feedback forums and add your own take on the tile transparency
or find the idea that best describes what changes you would like to see made to this feature. If you find an idea similar to what you want out of the feature you can just add your own comments to the idea to help further explain your vision. Cheers!

Adjust tile transparency
Adjusting the tile transparency allows you to better view your custom background through the tiles on the screen.

Note You cannot change tile transparency if your background is set to a solid color.

To adjust your background:

1. 1. Scroll left on the Home screen to open the guide.
2. 2. Select Settings.
3. 3. Select All Settings.
4. 4. Select Personalization, and then in the right pane, select My color & background.
5. 5. Select Tile transparency on the My color & background page.
6. 6. Choose the transparency that you prefer (Solid, Mostly solid, Partly transparent, or Mostly transparent).

I tried a few different backgrounds and I would like an option as some look better with solid colours!

It's another nice addition though

so the enhancement is an enforced change. Really should be an option. I like the idea but as an option!

For any feedback related requests it's best to reach the dedicated team by following what's mentioned here => Provide feedback as an Xbox Insider | Xbox Support.