Jake

I think the big reason why Konami ported the PSP version of Castlevania Symphony of the Night (and the included Rondo of Blood from that release) is due to the reworked English script of that version that they claimed felt more natural as well as the fact that Requiem was the first of the Castlevania collections on modern consoles and resorted to porting a collection already made a decade prior over a brand new collection entirely to test the feasibility of such a thing going forward. Aside from that, the only thing keeping us from getting all the regional variants and the artwork in a future collection is probably the same thing that worried Konami back in 1997 with its original release and the Koji Igarashi directed remake of the PC engine Castlevania for PS1 called Castlevania Chronicles (which had a Symphony of the Night art gallery) in that both games contained nudity that had to be censored (SotN had pixels redrawn and Chronicles had the character art completely recropped to remove the offending portion) in order to gain a Teen rating over here in the US.

Edit: Corrected spelling errors or word changes created by the useless auto-correct function.

Or, and hear me out, they could recreate an experience that GBA owners got in that they could bundle it with Windwaker HD and separately with Twilight Princess HD similar to how A Link to the Past had the prior Four Swords game bundled in with it. Seeing as the game heavily relies on sprites, I would assume it doesn't take up much space and Nintendo probably wouldn't waste cartridges on that game alone but bundling it as a free multi-player experience with two other bigger titles would not only help justify its cost, it would justify its inclusion on a cartridge and would help maximize the number of players who have access to it as some fans may prefer one of those 3D titles over the other.