So, I finally bit the bullet and upgraded to QGIS 3.2.3 Bonn. However, for layers that are not turned on the font is a super light grey in the layer panel and I can barely read it. How can I change what this looks like so I won't need to get glasses in 6 months?
This question about changing the background color of the layer panel may help. They recommend the Load QSS - US Themes plugin. Try the themes "dark" and "wombat." The other themes actually make it harder to read deactivated layer names.
You can also create your own UI theme using the examples that come with the Load QSS plugin as templates. The qss files for these examples are available on GitHub: https://github.com/All4Gis/Load-QSS/tree/master/examples
Or you can change some display settings in the Options dialog (Settings menu > Options > General). Unfortunately you can't change the font color, but the night mapping* UI theme may help, or enlarging the font.
*There's a bug in QGIS 3.0 where switching to night mapping mode might cause QGIS to crash. https://issues.qgis.org/issues/18669
*There's a bug in QGIS 3.2 where you can't turn on night mapping mode. https://issues.qgis.org/issues/19944
Here's a rather silly workaround. Put every layer in its own group with the same name as the layer. When a group is disabled, the group name is still displayed in black.