Material design is like bootstrap for mobile. Good to give devs something they can't mess up too badly, but is pretty soulless.
Apps that follow it will all have a similar look and feel on a platform... however, you can still make both good and bad UIs within that (or any other) framework. It doesn't alleviate the need to work with a UI designer.
There are certainly a fair number of developers who will just download a Material-styled template. But please don't assume that you can't do much more.
Take a look at some of the showcase designs on the Material Design Lite site for examples: https://getmdl.io/showcase/index.html
What does that mean?
I get that opinion. But allow me to play the devil's advocate:
Mobile interfaces are small and restrictive. Touch screens and gestures have zero discoverability. Interfaces must scale to a multitude of different screen sizes and resolutions. Flare hurts usability in these situations. When designers break convention it is far more likely to result in confusion or frustration by end users. Well defined standards can enable me to use your app without even looking at the screen and drastically improve accessibility for things like screen readers.
I think the tendency toward flare stems from design education that emphasizes print media and tries to make a direct translation into Web/UX Design. Print media, and advertisements are meant to grab your attention, establish unique brand design language and brand identity. But If I'm already on your website or using your app you already have my attention. You've already sold me. Now simply help me accomplish the task I am here for in the least painful way possilbe. Branching out beyond common guidelines and creating new interface conventions may scratch your creative itch but it is rarely more efficient or easy to use that established conventions.