Interchanges were originallay planned, designed and built for safety..........
As time has passed, land costs have risen (corners are worth more for developments), and the tightest curl you can pave is the norm. Don't waste fuel and track on a lot of grading, just pave the terrain as it lies. Look at your older interchanges in the more open spaces around cities.
By the way, we were still running US80 from Jax, MS to El Paso in 1958. NM was in process of
going 4 lane past Deming toward Lordsburg. Interstates are still a novelty to some ole guys...