Increase in difficulty by having Townies spawn with random stats and skills so if they are assigned to a job they are not very proficient in they can cause accidents that require other townies to clean up the mess (Fire Dpt, Police, Animal Control, Health Inspector, Cleaners, etc) or assigned to jobs they are great at and bring in more attraction/money. Good Skills can be fun/goofy and mixed with bad skills to cause more chaos if Mayors decide to bite that bullet, thinking of Oxygen Not Included in this regard.
If Townie general cosmetic randomization is coming I think this random stat/skill could also mix very well both in challenging Mayors with making more meaningful decisions when managing shops/what they sell and also Mayors having more fun with their Townies and hunting for that one awesome Townie that will change your entire situation! Plus plus this would spawn more Townie jobs if this introduces accidents like fires, crime, floods, rats/insect infestations etc.