I see merit in both approaches. The emulation approach preserves the original experience, which is valuable when you want to experience the work in its original form. This is great for scratching the nostalgia itch, as well as anyone who wants to study the original work. The porting approach transforms the original work into a form that is approachable to the modern game player. This is great for people who want to play a game but are not as concerned with a "vanilla" or the as-it-was-released experience. This could mean the port surfaces new controls (touch controls for phone/tablet devices), or applies quality of life changes to patch out frustrations.