Well the idea about this thread isn't just that they're easy, but conceptually and technically boring/uninspired. At least for the most part. There are outliers of course, like the zombie trio.
Despite the fact many people think the boss design is lazy, I do appreciate that Medusa also retreats when Alucard wears the Mirror Cuirass. If there's one thing SOTN doesn't lack it's the little details.
Although I really liked the Nightmare sequence, I thought the Succubus was rather uninspired. I know she wasn't Carmilla, but just look at her in COTM, she was a much better boss.
Speaking of Medusa for that matter I thought SOTN and LOD's Medusa boss battle were fairly similar, but that boss battle was more fun and worked much better in 3d than 2d.