Every business has different needs when it hires a new employee. But regardless of company size or type of industry, it's a good idea to present new hires with an offer letter that outlines some of the critical terms of the employment relationship to set initial expectations, introduce your culture, and minimize future legal risk. To achieve a tone that does not become "too legal," it's a good idea to include information about some of your company's policies that reflect your employment philosophies and employee programs that the person may find beneficial. You may need to customize the letters for different people and positions, but it is worth the effort in the long run because if done properly, it will help minimize legal risk while communicating about standards and expectations in the workplace.
Some smaller businesses do not like to use offer letters because they are inexperienced with crafting the wording and may view them as overly legal and officious. But keep in mind that, in this day and age, most people have come to expect offer letters will contain some amount of legalese and "cover your back" terms. So don't let this dissuade you.