I believe that a DC fast charger in combination with a 3+ kW AC charger is the perfect combination for any electric vehicle. The goal for any EV manufacturer must be to achieve DC charging times between 15 to 20 minutes. So I totally agree with the strategy of Energica for example.
The faster you can charge, the lower the importance of a big battery becomes.
So while the additional DC charger is additional cost to the bike, you can keep overall costs lower by saving on the battery as the battery is the biggest cost for an EV.
The only thing left is to make sure that the battery size is tuned to the application; commuter, touring, sports, off road, etc.