I mean MCU, particularly Iron Man has become so popular for more than a decade now. It's like it somehow has overshadowed DC and Batman today, the way I see it.
Yes true, Iron Man won this decade, but Batman was winning for Decades
Batman too have very popular & loved Movies (Batman Trilogy), not to mention that 90s Batman Movies were among first successful Superhero Movies, and also don't forget that Batman is easily way way more popular than Iron Man Comics wise & also have big video games fanbase thanks to excellent Arkham Series Games
Edit: Batman Animated Series is also an amazing show & very successful one, so not only Batman attracted many Fans for very very long time, but it attracted from different cultures, unlike Zoro for example who is only for Anime/Manga Fans & that's it