"Hyu. management has been reactive to the overwhelming EV market demand. They never became proactive with a realistic BEV market vision" and more at: https://cleantechnica.com/2020/02/16/hyundai-gets-serious-on-electric-cars-still-does-not-understand-demand/
Dealers don't promote EV's because they don't make any money from servicing and maintenance, which is half their income. Their love for fossil cars keeps the electric far in the background. Example, the dealer I lease my Kona from has had 2 more 2019 EV Limiteds for a year with no price reduction, and unless you do a specific search on their website you'd never know they were there. Physically they're hidden from view in the back of their lot and if you ask to test drive one they'll tell you to come back in a couple of days when the battery gets charged. Most potential customers lose interest at that point.
This could be a problem for all legacy automakers. It happens to be a problem for Hyundai/Kia now because they happen to have a halfways decent BEV.
You're right, we don't see advertising for the Bolt either, do we? In the meantime Tesla is going full speed ahead with affordable battery development and charging infrastructure and will probably command the market for a long time. However, the announcement by GM that it's building an exclusive EV plant in Michigan indicates there might actually be some promotional activity eventually.
If dealers were smart, they would install a handful of DC fast chargers on their lots with usage fees. That should more than make up for a loss of revenue for simple maintenance such as oil changes...
I like your thinking, they have to diversify, and don't stop there. How about restaurants (a nearby Ford dealer does have one, actually), coffee shops, etc. within the dealerships? Potential draw to their showrooms as well.