Anything requiring any amount of nuance just wasn't an option then or now.
I think the nuance would have been ok because most people don't understand the computer rankings anyway so changing from one formula they don't understand to another formula they don't understand wouldn't be a big deal.
I kinda like the square root idea posited above by
@Cincydawg but I think that might be too nuanced. With a cap of 21 you could just say "It is capped at 21 to disincentivise piling points on hapless opponents." The square root thing more-or-less accomplishes the same thing but it is too complicated for a lot of people.
I don't know if the computers already do this but I think it is very important to look not just at final score but at what the committee has called "game control".
The examples I always use are two Ohio State games that I attended:
In the mid-90's the Buckeyes had a game against Iowa in which Ohio State just obliterated the Hawkeyes. At one point Ohio State led 56-0 and the game was never in doubt. However, Ohio State's backups, third stringers, waterboys, cheerleaders, and mascots got outscored 35-0 such that the final score was "only" a three-TD, 56-35 win.
About a decade later the Buckeyes beat Penn State in a tough and very competitive defensive slugfest. In the first ~55 minutes of the game the only difference was that Ohio State had done better in goal line situations such that the Buckeyes had a 14-6 lead on two scores for each team. With time running out Paterno was compelled to let his QB sling it around and Ohio State promptly scored 14 points on back-to-back pick-6's for an impressive looking final score of 28-6.
I use those two examples to illustrate the point that the final score can be misleading. In the tOSU/Iowa game the Buckeyes could have won by 100 if they had wanted to and the 21 point MOV severely understates Ohio State's level of dominance. In the tOSU/PSU game it was a hard fought game and the 22 point MOV severely overstates Ohio State's level of dominance.