The problems I see are the cars don't have the range to do more than a few laps (I hear this is a cooling issue and the cars aren't actually being let fully off the leash), which makes it hard to get into, there is also the issue where there are only 5 races in a reason due to everything floating about on a boat which again, makes it hard to get into, its not really the sort of series where you get a lot of people going to watch it at the actual event itself, its all on TV, makes it hard to get into...
When the Extreme-H series is launched, this will run alongside the Extreme-E stuff so might make things a bit more interesting, but probably not enough to get a huge increase in viewership.
That said, because it's new and all of the teams are all in the same boat the comradery is pretty good, to see all of the mechanics chucking spares at each other and helping out, drivers are all pretty approachable and its all a bit new to everyone, but you don't see that on the TV, you also don't see that its ran to TV schedules which means stupid track hours lol..