Because this show is quite mathematical in its inception:
Sailor Moon + Gundam + Dragon Ball Z - bullshit = pink explodey death things in a cute package that kind of looks like a mecha
Why would I want to be a part of this series?
Well, all the relevant main characters are basically famous mecha (Gao Gai Gar, Mazinger Z, various Gundams), packaged as magical girls, all of whom actually LOVE their jobs, and who each have enough firepower to level a city DBZ-style. The fact that over time, it went from being a Cardcaptors knock-off to Star Trek with Gundams is also a plus. At one point, they just gave up pretending to be a magical girl show and just had a small fleet of these superpowered people serving in what is basically the United Federation of Planets.
Their weapons and spells are also quite versatile and the heroes are consistently making new tricks.
Wait....
...Superpowered space police/paramilitary organization...with intelligent/semi-intelligent weapons that respond to their will and imagination....
Nanoha is part of the Lantern Corps!
Even more reason to join!