The owners of the trading cartel in highsec will like this change. Looks like CCP again helps the big players to secure their dominance.
Hint: the more balanced change would have been to divert a minimum broker fee also in citadel trade. But guess what? This would take development effort instead of changing a number in the database.
In general everybody in RL economics knows what a high Tobin tax leads to … dry up markets, black markets, people seeking alternatives … anyone has a good channel for arranging big sales contracts?