Your question asks for both editors and reviewers but goes on to focus on editors. I will thus start with editors.
As you say editors are not generally listed on electronic copies of articles. Being Editor-in-Chief of a journal, I along with the other Associate Editors, do not see any need to be visible there. The reason is that one can ask to whom the credit has meaning.
First a practical issues. For my journal, we are all listed on the journal web site. When a person chooses a journal the line-up of editors is one criteria to use, if you recognise an editor as a prominent scientist in the field, it is a good (although not fool proof) indicator that the journal is good. So from that perspective nothing is lost. I think for most this is the most important issue of seeing the editors names for most authors/readers. Finding the web site is not difficult so I am sure the names can easily be found.
As for credit, I feel I am credited enough by having the job listed in my CV. After all, apart from enjoying the work associated with the editorship, it is a good experience to show in a CV for salary discussions, science proposals etc. That is where it counts for me. I would not be much happier if my name was listed on every paper "my" journal puts out. Besides, if an author experiences I have provided a service beyond any normal editor's tasks they usually thank me in the acknowledgement but that is not something that is common (and should not be) or expected.
As for crediting reviewers is should be common courtesy to acknowledge at least very constructive reviewers, even anonymous ones (as anonymous), in the acknowledgement. Unfortunately there seems to be a tradition in some academic cultures never to do so. One possibility is also for the journal to list reviewers in a "thank you" page although that carries with it other issues.
So on the whole, for editors, I am sure most editors are quite happy the way things are (or they would find ways of changing it) and in the case of reviewers, authors could improve when it comes to acknowledging the work.