>>22123424So you don't know what gender the pokemon is.
For example if Ash's Pikachu was refered as a female before gender differences where introduced you had a major continuity error in hands.
Also, some episodes of the anime rely on the surprise like Ash's Pidove not being affected by Snivy's Attract.
A great example of this would be Mr. Mime. Its original name is Mimen, but they decided to localize it has Mr. Mime, which wasn't a problem befor genders where introduced, but nowadays we have female Mister Mimes.