Surge protectors help in two situations, a 110 AC connection that has a problem (not at all rare in RV parks), and in areas with lots of severe electrical storm activity. Worst area by far in the nation is Florida and not all that much better are parts of Texas.
The more expensive the electronics the more worthwhile it is to invest in good surge suppression. Big difference between my first camper that only had a 12v water pump and tungsten lamps and my current one with electronics in the fridge, stereo, LCD TV, furnace thermostat, and inverter to which I took up laptops.
Each new generation of computing devices is more vulnerable to voltage spikes. The chips are faster and have more "transistors" in small spaces so there is less insulating material between them and it takes less of a surge to blow out a section.
The suppressors to avoid are the ones that a basically a power strip with a MOV chip soldered in place. The chip blows with the first surge and after that the attached equipment is more vulnerable than without the power strip.
Add up the cost to replace every piece of equipment in your RV that has electronics, including computers and satellite receivers and routers, and then compare that to the less than $200 price for a good surge suppressor.
What you were able to do 20 years ago is ancient history and best to try to stay abreast of the changes.