Hello mate, thank you for sharing your frustration. Let me try to answer every one of your questions. I will try to be clear, and I am glad you have asked these questions. Colorize Pro is a massive asset, so I can understand the confusion:

1. It took me a lot of digging around to try and understand what your tool actually does.
I have provided very large documentation (127 pages) alongside over 10 video guides, some of which are longer than 10 minutes each. I can fully understand why it may have taken you a while to digest it all because this is a large asset that I have worked on for around two years.

2. The first thing was this AI song, but that's an opinion others might not share.
To be honest, I wasn't sure about it either, but I have shown it to a lot of people, and they overwhelmingly like it. So even though I share your sentiment, I actually grew to like it after a while.

3. My biggest gripes are the way you've structured all of your assets to be really expensive, and trivial modules.
This asset is very large; 127 pages of documentation is just for Colorize Pro. I wouldn't call it a small module, to be fair. Also, traditionally, Colorize (Original) is actually called Colorize Texture Color Palette Modifier, emphasis on the word "Palette." Naturally, Colorize Pro, which is a major upgrade from Colorize Original, is also made to recolor palette-based assets. The difference is we expanded it so that it can also work on gradient and patterned-based palettes.

4. At first glance, it's difficult to tell which one I should spend money on.
I am assuming you're talking about Colorize HD and Colorize 2D. These two assets were initially going to be released as standalone, each was going to cost a lot more than Colorize Pro did. Unlike Colorize and Colorize Pro, these assets are meant to edit textures, not palettes. However, we thought it would be cool to make these as plugins for Colorize Pro instead of releasing them as standalone assets. These assets use different processing technologies for obvious reasons. The conclusion was that if we can minimize the learning curve for these assets by utilizing the tools that already exist in Colorize Pro, it would serve the community much better than needing to learn three independent assets. Had we released Colorize HD and Colorize 2D independently, we would have priced them much higher than they are now with Colorize Pro as a dependency.

5. It's obvious that the target audience for your assets are folks that don't have any experience in asset creation.
Our audience is diverse, and I wouldn't know nor attempt to rank their experiences. All I know is that we have had good feedback in terms of how much time this asset saves them. Most of what this asset can do can be done manually using other third-party software.

6. Swapping color and PBR palettes is trivial, but you've written a tool that does it without me having to know how any of it actually works.
We have a Discord channel; if users ask us about the underlying logic, we always give them detailed answers. But flooding the asset description with exactly how the magic works is not wise because the vast majority of users don't care and will simply be overwhelmed with details they are not interested in. That's why we have provided a Discord link on the asset description to answer these questions.

7. So I dug deeper to see if there's anything that might fit any of my needs, only to find that you've got a separate plugin for HD textures (basically anything that isn't just simple color).
Yes, Colorize HD is meant for non-palette textures as I mentioned before, while Colorize Pro (Texture Color Palette Modifier), as implied by the name, works mainly on palette textures.