Too many questions for me to remember, so I'll just throw out some answers and maybe they'll match up to some of the questions
Procedural textures - I've never seen any that were very realistic. Even Alan doesn't use them, and he won an Academy Award for computer effects.
Mipmapping - nearly all Direct3D programs use them, and MA is no exception. A mipped texture is 33.3% bigger (in bytes) than a single-level texture, so they are not a byte-saving item, but a visual-quality item. When a 3D object goes off into the distance so that its size is only half what it was when near the camera, the graphics system has a hard time deciding which of pixels of the original large texture to display on the now-small object. This causes aliasing, or sparkling of the texture. With mipmapping, it just switches to the next smaller picture, until it finds one which more closely matches the size of the object on the screen.
Lionfish barbs - The new Lionfish does have polygon barbs on its head. The barbs on the fins are in the textures. Yes, all the new fish will have more polygons than the existing fish, but the added realism will mostly come from bigger textures. A high-res texture with alpha will automatically anti-alias itself when stretched, but the only card that I've ever seen perform a decent job of polygon anti-aliasing is the now-obsolete 3Dfx series (and then only when using its native Glide language).
I wrote MA to squeeze every last bit of realism possible out of an 8-meg card at 1024x768. Sure, a lot of people still have these cards, and for them MA 2.6 will continue to be sold and supported for years to come. Now it's time to move on and give the people with systems made in THIS decade something to look at.