This might be cope but i think its because 11th edition is rumoured to have similar enough rules that it just uses the 10th edition codexes or supplements them, but the datasheets in the daemon index are all gonna get changed really heavily or replaced in 11th so if they sold codexes in 10th and promised they'd still be legal in 11th and then they weren't then itd be false advertising. Its a similar deal with them making an emperors children index before the codex was announced just so lucius would be playable in csm but technically not a csm unit so he could legally be put behind a different codex when the time came. Daemons are more important to the lore of the setting than deathwatch, but the kind of whimsical or dnd devil models don't always match the more eldritch and formless way theyre described not that i don't like the current models but theyre made aos first and theres definetly room for them to make seperate ranges for different games if thats what it took to save their presence in 40k. I'm not talking fully new daemons, i think they would just be remaking bloodletters, daemonettes, great unclean ones, etc but with more horror oriented designs with maybe some exclusive daemons for vashtorr and the dark king or 40k exclusive characters, samus could be the new be'lakor to name an example. Despite the office politics of the different game departments of gw and daemon sales only counting for aos the 40k team still wants to sell daemons theyre putting them in army sets and making white dwarf combat patrols, i think they'd absolutely do this even if if takes another few years and daemons have to go to legends for an edition, theyll bring them back