It was highly irregular, and considering how much of police and prosecutor actions in Sweden are based on professional ethics, rather then laws themselves, the level of irregular behavior clearly stands out in this case, as it also did in the pirate bay case, but that's a story for another time. Yes, we really should put more of the rules for police and prosecution into law, there's too much leeway as it is today.
Back to the topic at hand.
Rape cases are usually not public, they almost alwaya are played out without anyone except legal teams, judge, prosecutor, lay judges present. Thus since the trial is in private, and an exoneration in court is then less 'visible' than the public "accusation" cause by naming the suspect, the view is generally that the courts and prosecution should not explicitly name people in the kind of cases you expect to be held in that setting, or in generall - cases where publicly naming suspects can cause undue harm to the suspected regardless of the veracity of the accusations.
It was as far as I can recall still unusual for any accused to be publicly named, much less so for cases expected to be tried behind locked doors. Usually public naming of suspects only happened if the suspect was deemed to be violent enough that the public needed to be warned.
This to me suggest that irrespective of whether or not Assange is guilty, the prosecutor mishandled the cases - parts of the charges had to be dropped because of the statute of limitations because they failed to act while he was in custody in the UK while arguing over something a Swedish judge has now said is not a prerequisite to continuing investigation.