>more races
Problem: the new races will be shallow. The game's mechanics are developed, but the game currently has a one-size-fits-all approach to its races and characters.
Example: a small flying creature (such as a fairy) ought to have a special role in combat. They can't wield heavy weapons or deal much physical damage, but they are very difficult to hit, they can flank past enemy tanks, they can harass/interrupt enemy spellcasters, or they could sneak past the whole battle to steal important loot or free a hostage. Most of that cannot yet be achieved via modding. Fairies can be agile and good at magic, but that's about it.
Elves are also supposed to be agile and magically talented. This ought to manifest itself in different ways. Instead of being too small to hit, they should be graceful and evasive. Instead of flying across the battlefield to distract the enemy healer, they could pin down the enemy healer with arrows. A fairy might use magic to confuse and disrupt her foes, while an elf typically uses it to enhance her own abilities. An elf and a fairy ought to behave very differently in terms of the jobs that they can perform, their interactions within the mansion, the sexual actions which they prefer, their tolerance of various drugs or foods, etc. But at the moment they're somewhat interchangeable. Even fairy wings are essentially just a cosmetic variable (similar to skin color); the ability to fly is almost never relevant for gameplay purposes. It's possible for modders to create bizarre cosmetic combinations (e.g. blue-skinned quadrupedal winged gnomes), but it would be difficult for modders to make a new race feel unique and special.
Imagine that we create an ogre race. Now try to imagine how they would differ from the existing orcs.
"Gruzbar the Orc strikes the foe with her warhammer for 14 damage!"
"Bazgrub the Ogre strikes the foe with her warhammer for 15 damage!"
"You insert your dick into Gruzbar's green orcish butthole! Gruzbar has an orgasm! You gain 2 mana!"
"You insert your dick into Bazgrub's grey ogrid butthole! Bazgrub has an orgasm! You gain 2 mana!"
Now imagine that horns become mechanically relevant during gameplay. Perhaps they can be used to strike in combat, or a horned character is unable to wear armored helms, or horns can be used for leverage during oral sex. The fact that ogres have horns (while orcs do not) creates an interesting dictinction between two races. Imagine that body size becomes mechanically relevant, so that large creatures are much stronger but also more resource-intensive (they need larger rooms, more food, etc). The fact that ogres are larger than orcs is now meaningful. It might now be worthwhile for modders to create an ogre race.
And - as you've pointed out - the artwork collection is probably large enough that there are already a few ogre portraits available :)