I suspect most of the piracy in those apps was among people who were never the target market. Someone who wants to make funny cat pictures, or even edit photos they took with their $300 point-and-shoot camera isn't going to pay $400 for Photoshop.

Professionals who make their living using Photoshop usually don't have much trouble with the cost, whether paid monthly, or occasionally when a new version has a feature they care about.

Being able to bring in some more casual customers with a lower initial cost is just a bonus.

No, since that's orthogonal. You can pirate with or without a subscription.