While I´m a purist myself and personally perfectly fine with never changing anything beyond the already announced QoL changes, there is a demand and possibilities for changes in the future.
That´s why I think it is so important to clear that beforehand - before they might make the current version not playable in its resurrected form anymore.
And since D2 Classic and LoD won´t be changed anyway, I don´t see the extra amount of work to keep these versions going.