I have to agree with you completely. I have loved X Japan's music for a long time and have also equally admired them for the fact that they have got their name, music and image to such a point that whatever they release, (this may sound like the beginnings of a rant about how their music / products are over priced and that they have been dishing out re releases for years, but it is not), always sells very well.
Although it has a lot to do with Yoshiki as an artist, I think what Yoshiki has done with X's tracks through Eternal Melody I & II is amazing. Here he has produced music that has an appeal to both rock and heavy metal fans and turned it into something that catches the eye of classical music fans around the world. With the release of the classical versions of X Japan's music, Yoshiki bought the X Japan name to a new market, to a new audience.
And you only have to look at the limited edition releases in the 90's as well as the box sets in the 00's onwards to see that they have always taken advantage of demand. I have always found it interesting to look at what music they currently have in print available. For example, Vanishing Vision has been out of print for a long time, I believe the last re release was in 2000? I feel this has made a demand for this product so if they do ever release a remastered version of their debut album, it would sell very well. (Yes I am aware that it is available on iTunes...) Similarly Dahlia is not easy to get a new copy of. I don't believe it is available digitally anywhere, (legally...), and there hasn't been an individual physical release in print for a very long time. I found it interesting that you could actually buy a copy of Dahlia through way of paying a large sum of money for the Complete II set (which I also believe at last check was being shown out of print on several online retailers...).
I do believe that when X Japan release their new album, they will take advantage of the fact they have such a dedicated fan base, (this isn't a bad thing), and release several version, allowing to capture more completely the markets willingness to pay, (a group of fans will only be willing or able to buy the regular release but there will be those that will be willing to pay substantially more for a special version...the box sets vs. their individual DVDS are an example of this).