Orcs and Klingons may have been novel in their time, but the trope of an entire species sharing the quality of "warlike" is, at this point, a tired one.
In all fairness the Jem'Hadar were pretty interesting though
EDIT 1: Expanding on that idea it need not be a deity or
The Founders that are directing their warlike tendencies, it could be influenced by their particular diet (food, herb, tainted air or water supply, influence of the corrupted magic their shamans utilise...etc) and they are but unknowing victims.
EDIT 2: Perhaps orcs are born inherently
weak and they undergo a specific ritual to gain their might but in so doing they gain these warlike tendencies. Now in times of prolonged peace you have some orcs who decided not to have the ritual performed on their young and ofc this leads to complications within the people. These non-ritualised orcs are actually half-orcs.
Truth of the matter being that the orcs were descendants of a large contingent of humans that migrated out into the wilds* but they have since forgotten their ancient roots. Those few in the know within the orc side keep it quiet and push to exterminate the half-orcs and maintain the rituals for fear of the truth being revealed.
It may also be that it is the humans that are maintaining the conflict, some of the human elites know the truth and seek to either wipe out the orcs once and for all or ensure the orcs keep performing their rituals on their young to ensure the divide between orcs and humans continues to exist, thus safeguarding the
purity of mankind. Diplomacy with these accursed people is out of the question.
*there they encountered the goblinoids, the ogres, the trolls, the gnolls...etc and in a desperate attempt to survive, the ritual came to be - whether by discovery or as a dark gift.