My truck had a couple ball joint boots that were busted. The service writer said that he wouldn't recommend replacing them because they weren't loose; just keep an eye on the grease. I went ahead and did them because I was headed cross country with a travel trailer in tow and didn't want to take any chances. I think I'm going to go ahead and do the bushings, etc this winter so it is ready for camping next summer.
If they aren't loose, use your own judgement on doing them. If you're tearing the whole thing apart anyway, you might as well do them if you can. They aren't cheap to have done in a shop, that's for sure.