If I understand correctly, then Cloudflare's paradigm is: We have a bunch of polished, simple standard services and if you want to do something slightly different and/or do something on the network you can use Workers.
I think it's pretty smart and empowering as it strikes a nice balance between great, simple DX and high flexibility.
Currently "Image Resizing" requires the Business plan or higher, so this strategy will not work for most hobbyist. Seems like enrolling into "Cloudflare Images" does not give a way to use this feature from Workers.