I don't know if that was Midjourney's intent, but it seems like a smart approach. Instead of trying to be everything to everyone and generating quite a lot of ugly garbage, you get consistently good-looking stuff in a certain style. I'm sure it helps their business model.

Feels like it's the Instagram model for prompt-generated images.

Anyone can get a camera phone, take a picture and use some free software (e.g. gimp) to get great results in post-processing.

Most non-expert users though want to click on a few pre-defined filters, find one they like & run with it, rather than having more control yet poorer results (precisely because they _aren't_ experts).