If I'm in a situation where the 85D doesn't have the range to make the trip, it's very likely the 90D wouldn't manage it for me either. For the minor incremental range increase, I don't think I'd do it even if could be magically added to my car by paying the design studio difference - let alone the real cost of a trade.
I think the range I have is acceptable and if there are improvements needed, it's in the availability of charging infrastructure. Another 15 miles of range isn't going to appreciably change the number of times I'm stuck to stop for a charge, or the time I'm cooling my heels waiting for the charge to complete. A full charge will take longer on the 90 than the 85, by the amount of 5 kWh, so in theory, stops would be slightly longer anyway, just marginally less frequent. Except that infrastructure isn't so plentiful yet that you can typically pass a charge station and go another 15 miles to another one. Around here, many trips require you to stop where the charge station is and top up when you can - there isn't any flexibility! 90 kWh won't change that.
At some point, adding range is going to be like adding a second fuel tank to your F350. Not really necessary except for a very few, or those who just don't want to stop at a gas station as often. But the gas stations will still need to be available before you finally drain the second tank...
Think of it another way... if your ICE car model had improved fuel economy by 5% in the next model year, would you have traded for that alone?