I suspect this move is due to behind the scenes Adobe / Apple relations souring over the years.
Adobe used to be one of their biggest supporters and helped winning over users to the Mac platform.
This has diverged significantly over the years, and I think Apple is looking at Adobe and their business model and realizing that it both lucrative for them to have software that fills into this market to round out their creative pro apps suite and that Adobe increasingly becoming aggressive with cost / licensing and tactics to extract revenue aren't good for their ecosystem.
Adobe used to be one of their biggest supporters and helped winning over users to the Mac platform.
This has diverged significantly over the years, and I think Apple is looking at Adobe and their business model and realizing that it both lucrative for them to have software that fills into this market to round out their creative pro apps suite and that Adobe increasingly becoming aggressive with cost / licensing and tactics to extract revenue aren't good for their ecosystem.
That's my working theory, at least.