You misread. let me try to explain better.
The problem isn't that it's "hard." "hard' is great for an arcade game. Quarter-munching is great. The problem is that you can't continue - the same thing that ruined the arcade versions of Contra, Super Contra, or Rygar (all remembered for their home versions, not the arcade games). When your game is designed to make someone constantly feed quarters into it to push through, designing the continue feature so you can't do that is a very easy way to keep people from feeding more quarters into your arcade game. Haunted Castle's design actually would have been okay as a home game, but as an arcade game it defeats itself.
Same difficulty as always, but without limited/four/zero continues? Just fine, and a worthy quarter-muncher.
Same difficulty as before, and same limited continues as before, but on a console? Also fine.
Difficulty and lack of continues in the arcade? What, the game doesn't want my money? Fine, I'll just play Castlevania at my house.