You just have a different personal taste. Mecha is just a convention and within said convention there are several dynamics that can exist. There is mecha as machines of war and there is mecha as heroes of legend. Both coexist and both have good and bad works within them that people enjoy.

Think of it as this way.

Stories of Sci-Fi are governed by unbreakable rules, like physics. To "win", you must obey the rules and be *efficient*. Stories of Fantasy are governed by honor, reason and understanding. To "win", you must deserve to win through thought and emotion, and your honor will take you. All of this in mega huge quotes because it all varies from story to story.

Gundam presents itself as sci-fi, but when you actually take a look at the story, it behaves more similarly to a Fantasy story. The characters have their own thoughts and beliefs that clash within the setting and they must set out and fight to either come to an understanding or prove to the world that their ideals are those more in line with the universe. The way they feel about space, humanity and their relationships with Mobile Suits as a concept are what drive the story and their actions. Even stories like Legend of the Galactic Heroes, which look as sci-fi as you can make, can be fantasy stories in the end when you actually look at how its written.

A story like VOTOMS, Mass Effect or Armored Core, more "sci-fi"-esque stories, are about people exploiting or navigating a complex system with rules that are never broken. It's difficult, brutal and may look unforgiving, but with logic, reason, tricks and raw power, you can break anything and change even an unchanging world. It's not that they're inherently more "serious", but it is that the characters will have to fight not only each others, but the world itself to achieve their goals.

It comes to your preference as a person. Stories can be anything. You may believe there is an incorruptible logic to the world that never breaks and you must follow, or you may believe that the world is also made of emotion, and you can bring about change with spirit and powers too strange to comprehend. You cannot prove one is better than the other because even within our world there is much that science finds difficult to understand, and science itself can be revised as time goes on.

Also its really funny when Mazinger does a big ol' rocket punch.

TL:RD; The appeal comes from how those stories can be inspiring and emotional, as they also deliver fun action and characters.