It would depend on how GMs process reports. If they have a record of all reports filed against a player, regardless of any action taken, you should report it, as it would allow the GMs to see a pattern. If reports where no penalties were issued are not logged/checked, there would be no point in reporting, as the GMs won't do anything based on a single report if the culprit doesn't say anything (could be an actual disconnect). Either way, your only immediate options are to wait or kick.

It's pretty bad when tanks do it. If the tank is kicked, anyone can leave without penalty, but only the healer will have a short queue if they decide to leave. If it's a trial or NM raid, you either wait 5 mins, which is a significant amount of time compared to the trial, or you pull and reward the dc.

That said, what would you suggest as a fix? Giving a penalty to kicked players would be used to grief and letting players leave without penalty if any member has connection issues would be abused. Being allowed to kick before 5 minutes have passed probably isn't an option for the same reason that there is no "difference in playstyle" option when attempting to dismiss, in that SE would prefer players don't immediately resort to dismissing others.