One of the advantages of cardcounting is that you gain knowledge of and can take advantage of the changes in probabilities of results occurring due to the cards remaining in the unplayed deck(s). A reading of any of the popular card counting books will make this all clear very quickly.
Card counting gives you information about the remaining cards. The information can be used for betting purposes and for playing the hands more accurately thus giving an advantage to the player. When using a count system the publisher/author will give critical indexes for most playing situations when it is correct to deviate from BS. (See Wong's Professional Blackjack). When applying the count and incorporating the playing index(the number)it is normal to use that number as the pivot point for the decision. Example: 12 vs 4. If the index number is 0 then you would stand on counts of 0 or more and hit on counts of -1 or less. The author of the playing strategy will tell you if the index is based on a running count or a true count. The more decks that are used (such as 8-decks)fewer situations occur when it is correct to deviate from BS.
Whenever you take the dealer's bust card you will attract the fury of the ploppies, regardless whether you played BS or not.Trying to explain to them that hitting doesn't alter the dealer's bust rate is hopeless. So I guess we just have to live with their anger.