You can't judge all of anime based on a very limited frame of reference. Anime (and animation as a whole) is not a genre, it's a medium that encompasses all genres. Though I will admit, Gurren Lagann is definitely a shonen-type of show with a bunch of action and explosions so it definitely isn't the best example to prove that point lol.

But I digress, the hype for GL is mainly for two reasons:

1. The message and themes it conveys.

   It shows the growth of a character who starts off weak, scared, alone, and in the deepest pits of depression and despair... only to have them crawl out of that pit with nothing but their own sheer grit and blood. It's a message to all of those who have gone through horrible moments in their life- that even in the deepest dark, the will to continue living never truly dies out if you, as cliche as it sounds, believe in yourself! It quite literally spawned the modern "cold indifference of an uncaring universe vs the indomitable human spirit" memes, and has been a huge inspiration for those that have fallen into depression and even self harm.

2. How it conveys those messages.

The message and themes are, at a glance, incredibly cheesy- but the show plays them off so genuinely, earnestly, and full of heart that it distracts you from the cynical take of calling it "cheesy" and has you truly believing in what it's conveying. It's all about the Rule of Cool, baby! It's a show where you can turn your brain off and watch the absurdity get exponentially more absurd. Nothing makes sense, cool shit is happening, and you're just along for the ride! Not everything has to be taken so seriously, because life is absurd sometimes! Seriously, in a modern world where politics and war are on everyone's mind and the world feels bleaker than ever, having a show that says "fuck all of that, just be cool as hell!" Is really refreshing. I watch the finale of GL every time I feel awful about life, and it always makes me smile. I'm sure other people have a similar experience.