Japan Anime is region A just like we have in the States.
The only reason i could see for having a modded player is if you wanted those same anime masters at cheaper prices, by buying the hong kong version or taiwan releases instead of paying the exorbitant prices in Japan.
Since you could pay as much as four hundred us dollars for a boxset of blu ray discs from Japan and the same could be had if released in the us for 90 dollars i think that is a very good reason to not import.
Depends on what series or movies are worth it to you and if they are true 1080P or shitty upscales as being animated only in 480 and not HD, of course anything animated on film is already good enough for HD.
Whether they toy with the colors or add dvnr.