The light block in the latest beta can change the light level, however, you cannot hold right-click it to continue changing the light levels. Instead, you have to click it one by one to toggle the light level.
Step to Reproduce
1. Place a light block.
2. Change the light level by hold right-clicking it.
The light level only changes once when you hold right-click.
The light level continues to change when you hold right-click.