From a sustainability POV, using living beings for milk production is vastly worse than a plant based alternative.
From a animal friendliness perspective, it abuses the same animals that would be slaughtered for meat, for long periods of time in cruel ways.
From a business and consumer POV, this limits your burger to only Omni and vegetarians, excluding the entire market of vegans, and people with dairy intolerances who would opt for this option instead.
All around a PR inspired, stupid half measure that is insulting at best.
lol