Benefits of Horizontal Drilling
A smaller amount of vertical well sites are needed to develop a reservoir.  Multiple horizontal wells can be drilled from a single site, reducing the environmental footprint. Some environmental areas that are protected from drilling can be accessed using horizontal drilling without harming what's above.
The cost of a horizontal well compared to a vertical well is substantial. This price can be offset by the significant increase in production rates. It can also increase production from formations that are minimal or deteriorated. Not all horizontal wells can produce at economically beneficial rates and should be used when viable.
Additional use of horizontal drilling is applicable towards ground water extraction, and to enhance bioremediation of soils, sediments, and groundwater.