I would lubricate the stabilizers and inserts. Doing the same for the switches ("all keys") would require you to disassemble the board, de-solder the switches, disassemble the switches, adding lube (see
this guide), reassembling the switches, re-soldering the switches, then putting the board back together. If you have the time and skill to take this extra step, go for it.
If not, adding the o-rings will be sufficient for quieting the noise from bottoming out the keys. To get rid of the
pinging noise that is common with clear switches, you can open up the keyboard and line the bottom of the case with rubber shelf liner that you can pick up from your local big-box retailer or hardware store.