In my opinion, I'd recommend using it. Sometimes, you might not have a computer nearby when you are debugging.
Here are some reasons against using it:
- It increases the cost.
- I would suggest checking with the manufacturer as I've never seen any price increase for adding silkscreen. If you are making a large number of PCBs, it might be a consideration, but you could add it during the development phase at least.
- Small components may not have enough space for the silkscreen.
- You can try keeping the designator of the component small as well (usually, Rxx instead of Rxxxx for resistors). This will result in smaller text, making it easier to position. In most cases, you can still add the silk, although it might take time and be tedious. If it's not possible, consider removing the text on components that typically don't require reworking or probing, like decoupling capacitors.
- The PCB looks more aesthetically pleasing without silkscreen.
- I agree with this point, but remember, we are not creating artwork here. The question is, what's more important: a beautiful PCB or one that's easy to debug?