If someone is averse to salt, for health or other reasons, there are rubs like amazingribs.com's "Memphis Dust," which doesn't contain salt. I'm not, so those rubs don't interest me. Yes, to answer your question, I believe salt plays a very important role in meat preparation. Whether you coat meat in salt, wrap and rest in the fridge overnight, or brine it, it will make a difference in the finished product! Salt causes a change in the protein molecules near the surface of the meat, that actually causes them to trap moisture inside the meat, thus making it more juicy because it retains that moisture. Check out
http://smokinitforums.com/index.php?topic=1504.0 for a more in-depth look at brining, and how it works.
As for types of salt - I'm a fan of Morton's kosher salt, and is pretty much all I use. But, I also know it is less salt, by volume weight, than table salt or coarse sea salt. Do a test yourself: Weigh one cup of kosher salt, one cup of sea salt, and one cup of table salt...you'll see a big difference! Getting to know how to use a particular salt will help you adjust accordingly for your taste. Kosher salt is coarse, yes, but much less dense than most coarse sea salts or rock salt, so you won't measure the same. Weigh salt, don't use a measuring cup, unless it's a proven recipe by someone who knows.
A lot of this question also boils-down to
taste. Cook a piece of meat with no salt, and then cook one with salt. Which is better? Salt has been one of the most-common food flavor-enhancers for ions. Let your own taste be the guide!