Fun fact: I just got back from Norway, and saw a Mach-E a week ago. Seen as it was apparently just released there "weeks ago", it must have been one of the first in the country.
I just checked the price of a MUSTANG 5.0 V8 GT, and the price is almost exactly double in Norway from what it is where I live in Mexico.
The small engine Mustangs have always been derided as non-Mustangs. It shouldn't be surprising that, as coupes become less mainstream, the share of the smaller engine declines. The bulk of Mustang buyers anymore are old men.
Plus, there's the issue that, speccing a ecoboost Mustang with some performance goodies puts it within spitting distance of a 5.0. The Ecoboost HPP is like $32k and the "performance" upgrades for systems like the brakes are essentially base GT take-offs. This makes the $37k GT a really good deal in comparison.
Factoring in depreciation, the GT is a better deal. Fuel costs are marginal since you can run the GT on 87 with almost no power loss while the Eco is a dog without 93 octane. And, for me at least, the GT is cheaper to insure (by like $3) than an Eco. Add in low-interest, long-term loans and the monthly cost difference is minimal as well.