When answering to "is-holding-memories-considered-bearing-a-grudge" I noticed that while נקימה ונטירה (revenge and grudges) are two explicit Mitzvos DeOrayso counted by Rambam, Smag, Chinuch, etc, both Tur and Mechaber omitted them.
As far as I know, those Miztvos should be relevant to our times. On the other hand, we know they had Rambam and Chinuch, so they were perfectly aware of these Mitzvos.
I heard some say Tur in his earlier editions included the reprint of Rambam's Hilchos Deos, but later it was removed. Anyway, Mechaber ignored them almost completely.
What could be the reason not to include explicit Mitzvos in a Halachic compendium?
NB: this question is very specific about those two Mitzvos. There's another question of mine about the general approach: "what-does-it-mean-halachicly-hamechaber-omitted-those-halochos".