Yeah, I thought the outer seals were to keep crap out of the tubes and from possibly reaching and potentially getting through your inner seals. If you keep them greased up and flexible enough, they do a pretty good job of keeping out mud, sand and other debris. The stock outer plastic caps aren't worth a damn. If you're getting work done where you have to pull the shafts, it's worth installing the outer seals, since they're fairly inexpensive, but I wouldn't pull the shafts just to install outer seals. I had my outer seals installed when I replaced my ball joints.
2018 JL Rubicon Unlimited, 6-speed, White
1985 CJ-7, 4-speed, 258 I-6, 3" Springs, 33" BFG AT, Gunmental Gray