In the Iwata Asks interview for Kirby's Epic Yarn, Nintendo President Satoru Iwata and Masanobu Yamamoto, the Character Supervisor at HAL Laboratory, Inc. discussed the early development of Pokémon Snap for the Nintendo 64.​ Below are the relevant excerpts from that interview.

Itawa Asks: Kirby's Epic Yarn Interview Excerpts

Iwata: Originally, Pokémon Snap for the Nintendo 64 system wasn't a Pokémon game, but rather a normal game in which you took photos, but the motivation for playing the game wasn't clear. We wondered what players would enjoy taking pictures of, and later on we made a somewhat forced switch to taking pictures of Pokémon.

Yamamoto: That time, adopting the Pokémon world clarified what we should do and the direction we should head, and I came to like Pokémon, so I felt like that had saved us.

Source: http://us.wii.com/iwata_asks/kirbysepicyarn/vol1_page4.jsp