Is pdfTex clearly labeled "do not use" and development has stopped completely? Also, do lualatex/biber/biblatex all have feature parity and are clearly documented as the "true" latex projects that are the only ones which should be used currently?
If there weren't two "yes"'s in response then OP's clear criticism will remain a problem. It cannot be escaped by advising the user to jump to a different branch based off the last downside they happened to describe about their chosen branch. (E.g., "I want unicode" -> "use lualatex", "I want WYSIWYG" -> "use SwiftLatex", "But what about unicode" -> "use lualatex", ad infinitum)
TeX/LaTeX is a rich ecosystem that has grown over a long time.
Over the last couple of years, pdftex, xetex and luatex have coexisted and pdftex was the stable choice and the other two were functional but in beta stage.
In the last years, xe and luatex became stable and pdftex entered maintenance mode.
WYSIWYG is an antithesis to LaTeX, but I'm sure it's possible to base something like SwiftLaTeX on luatex instead of pdftex.
This has changed only in the last few years.
You listed a few requirements, and while many are achievable using pdftex, only lualatex tikz all the boxes.
* unicode out of the box
* otf font support
* unicode in bib via biber / biblatex
* easy extensibility by writing lua instead of plain tex
there is more.
But only because luatex is out of beta, does not mean pdftex suddenly stops working or needs to be deprecated.
Is pdfTex clearly labeled "do not use" and development has stopped completely? Also, do lualatex/biber/biblatex all have feature parity and are clearly documented as the "true" latex projects that are the only ones which should be used currently?
If there weren't two "yes"'s in response then OP's clear criticism will remain a problem. It cannot be escaped by advising the user to jump to a different branch based off the last downside they happened to describe about their chosen branch. (E.g., "I want unicode" -> "use lualatex", "I want WYSIWYG" -> "use SwiftLatex", "But what about unicode" -> "use lualatex", ad infinitum)