It really depends on your driving habits. If you'll be supercharging daily or several times a week then there's definitely a benefit to the free supercharging. If you'll only really be supercharging on trips a few times a year then I wouldn't let free supercharging be a deciding factor.
For example, last year I supercharged 21 times and I have a 75. Let's say I charged from 0 to 100 each time (I didn't) and the electricity cost $0.15/kWh (likely lower). That's only $236.25. So for me, the free supercharging isn't a huge benefit. For others, like those above, it has saved them a good bit of change.
Edit: You can look up supercharger costs here:
Supercharging