If a happening occurs, that a particular person is responsible for. Should that happening be accidental or unintentional but it causes harm, loss or inconvenience to another, then a sincere apology, by way of the use of the word sorry is, and I say, is the least one should say and do.
If the occurrence could be envisaged by the person to be likely to offend, injure or cause loss to another. Yet if he still pursues his objective then an apology, or the saying of sorry, is only a means of escaping the consequences and should be viewed as such.
In a nutshell sometimes the word sorry can be acceptable but not in all cases for as you say Rayben - "why do it"