Hentai is actually so much better when you can understand Japanese, because now instead of having to reach subtitles to understand what is being said, the sexy girl is transmitting information DIRECTLY to you, she is speaking to YOU rather than speaking gibberish that you read subtitles to interpret like a cuck.
By learning japanese you are making yourself less cucked by removing a layer of disconnect, thus making self-insertion that much more easy in the scenes. I highly recommend it.