This study explores how recent design guidelines have focused on the visual variety of streetscapes making them more attractive. To date, this topic has been one of the most challenging parts of constructing walkable streets. We evaluated the streetscape features of Sejong City, recently constructed as Republic of Korea’s new capital city, and investigated their relationships with design guidelines. Consequently, we identified three principal reasons related to the design guidelines for the visual monotony in the street produced by the most up-to-date design guidelines compared with an ordinary street. First, the design guidelines cannot restrict the construction of large-scale buildings on the street, hindering visual changes caused by the zoning ordinance regulations because zoning regulations took priority when it comes to urban planning and regulatory governance. Second, design standards intending for a consistent street wall of buildings, which were used only in regard to the street enclosure standard, produced less spatial diversity and indistinct building bases, presenting weak vertical articulation. Third, applying the uniform standards for each building created repetitive architecture despite design standards for visual variety, such as recessed top floors, arcades, and retail uses for the ground floors facing a street.