I grew up not using the plural form Legos. But I also grew up thinking that it's important to never let a big company tell you how to speak.

Sure, but they defined the term. It's reasonable to follow the pronounciation. Intentionally doing the opposite is a pretty strange stance.

Still, people refuse to say 'gif' correctly either, so you just can't win sometimes.

Imagine obeying a corporation that doesn’t even pay you