The group may already votekick for any or no reason. The thing is that the request is twofold:
To display the reason and then likely to report the reason even if the reason is entirely illegible or empty and disagreeing with the votekick increasing moderation burden on Blizzard while effectively no rule is broken in the first place.
The suggestion to report actual harassment, which the player can already do so if any player actually harasses them through chat is already in place which is different from using the any or no reason kick which is not deemed abusive.
Incorrect, no report option is available for dungeon kicking as it is not against the rules. Only chat harassment may be reportable if any occured which is something I’ve already stated previous.
It is already not violating a policy of Blizzard. Namely:
The system is entirely under the control of our players. Players may choose to remove any other player from the group for any reason, provided the vote to kick passes. It is not deemed abusive to utilise the votekick as that is the intended design and vision of Blizzard thus far, that in your opinion should be changed doesn’t make it against the rules in the meantime.
I’d recommend to suggest any changes to the VTK through the ingame suggestion box but it will not likely include a report option for reason field votekicks.