Don’t think that adding lights to your toe-kicks is a frivolous aesthetics-only decision. Strip lighting at the underside of base cabinets is a great way to create a night light that looks fabulous.
In a renovation on the other hand we have to consider what effect a new skylight will have on the efficiency of the existing building. In some cases the additional sunlight (and therefore heat) can help reduce the amount of energy needed to heat the house. It depends greatly on the local climate but also on the design of the building envelope of the house.
Downlighting is just that: lighting that shines down to illuminate a space. Down lighting can sometimes be referred to as general lighting. Once it was simply the only light source in a room — that single fixture in the middle of the ceiling. If this is your only option placement and quantity of fixtures are the keys to attaining a balanced lighting level while reducing dark corners. Pot lights are also considered downlighting.