Model maker makes model training easy - train a model with just a few lines of code with input data from folders of data, TFDS or Kaggle. No need to worry about data preprocessing, how model training or transfer learning works or post processing etc.
Model maker also outputs tflite models with metadata which enables features such as ML Model Binding in Android Studio - inputs a tflite model easily into Android project, and auto-generated code for loading tflite model and run inference etc.
I wrote a two part tutorials earlier last year:
So the purpose of model maker as I see it, is to help app devs with very little ML / TensorFlow experience.
Hope this helps.