I would assume it's because younger generations of creatives are using their software less and less, increasing the risk of losing the market completely on the software side. At this pricing, more of them will turn to paying Apple rather than paying for multiple services, keeping them tied into the ecosystem.

Also so many people are paying for Canva, Capcut etc that taking a piece of that cake is quite a low hanging fruit if you have a distribution platform.

The acquisition of the Affinity software by Canva I imagine motivated this.

It’s even a similar pricing model, though technically with Pages / Numbers / Keynote covers a little more ground but I think the main intent is to get creatives using Apple’s creative software again

Pixelmator being the only 3rd party software because Apple never made a competitor to Photoshop

Though since Canva went full on toward more robust tools I imagine they have started capturing the entire editing chain more than they did 2-3 years ago, hence the Affinity acquisition