It's just for show. Like air intakes that aren't functional. It just makes it look more like all the rest of the cars on the road. You don't want it to get self-conscious.
That still doesn't make it a grille...
In terms of looking like every other car on the road...
Its funny though, Tesla excluded, all EV's seem to go out of their way to look different, to look like EV's, yet the grille is where they decide to keep a bit of mainstream? Thats bad logic...
Make EV's look like other cars, actually though, not the odd shapes BMW gives us, even the Volt ( i know not EV) looks so strange... Its no wonder that the best selling segment of Eco cars are hybrids, which LOOK just like regular cars...
Make EV's look like any other sedan/CUV/hatch = increased sales, just from aesthetics. This conspicuous consumption only attracts those who want to show they do their 'share'...
Grille is a strange and insignificant place to try and 'be like everyone else'