At this point we can only speculate what and why exactly happened, but I'll try to answer this to the best of my understanding. Palette lighting actually was there in SADX at some point in development. The fact that it can be enabled in SADX Preview with a working lighting debug menu suggests that it was in the process of being replaced by another lighting system, which ended up in the final version of SADX. I'm not exactly sure why the replacement was necessary in the first place, but if you enable palette lighting in SADX Preview it looks kinda inaccurate. Perhaps they couldn't get brightness calculation to work right, or maybe it was already on the way out. Either way, it looks like the basics of palette lighting were already there in SADX GC, but for some reason that was canned. Even with that new lighting system for characters and stage lighting, they could've done a much better job. For characters, they could've come up with better colorization values that would look a lot closer to the DC version, and doing so would've been very easy given the system they had in place - you can even do it yourself in SADX Preview. In fact the new character lighting thing works very similar to the Dreamcast version (with some added functionality like directional lights). It's just that instead of reading character palettes from PL files, it uses an algorithm that takes several colorization values and produces a palette that is then applied to the model. In SADX Preview, it can be previewed in realtime and there's even two color bars at the bottom representing base and specular palettes, which are exactly what's there in the PL files. They could've made character lighting almost the same, if not better than the Dreamcast version. But for some reason they just didn't. Also, in the 2004 PC port half of those colorization values don't work (but the data for them is still in the EXE). Morph suggested a while ago that it could've been related to DirectX limitations they had to face on PC at the time. Also, apparently the DX9-based Steam version has a shader that does character lighting like the Gamecube version, so it's possible that those values work there. For stage lighting, apart from making better use of the system they had (up to 4 different lights AFAIK), they could've imitated palettization using vcolors, which they sort of did in some areas like Casino, Final Egg 2 and the Mystic Ruins Chao Garden, but in most other areas it looks like a poor attempt to hide the lack of actual lighting. Or perhaps they were trying to make it look like SA2, who knows. I would say the game we ended up getting is the result of lack of effort and/or competence on the porting team's part. There are many things in SADX that suggest that the developers either didn't fully understand how their own engine worked, or were very, very lazy and/or under severe time constraints.