I don't know that low brow or trashy is how I would describe MK. It was always about over the top violence and the urgent threat to life as we know it. That's why the characters are serious. They have never been anything but.
The goofy looking people are a product of the goofy character design choices the MK team has made over the decades. Sonya Blade should probably have never been dressed in full body spandex if she was a special forces agent, but there she was. As queen of outworld Sindel probably shouldn't have been dressed in a leotard that was open down to her navel. As special forces Jax probably should have had a shirt on and real pants. But in those days some video game characters were expected to have more sex appeal than practicality. Now there are fans that expect certain characters to maintain their designs even though they may be kind of ridiculous.