Nepthu is a decent enough figure and his "Heroic" look is much like King Hiss but without that dumb Zorro mask. As for his boots, I think they made a good call and compromised his design so they could add a little more tooling dollars to the other more popular Filmation figures.
Had they given Nepthu his unique boots, they might have had to use Tri-Klops armor for Plundor or maybe they wouldn't have included Skeletor's axe accessory. Making compromises on possibly the least popular character in the Filmation sub was definitely the way to go. Keep in mind that this is coming from someone who prefers Nepthu over Plundor.