Eidos Montreal has a Tumblr account for gamers to pose questions for the developer to answer, and one anonymous fan asked if they had "considered increasing the amounts of ammo throughout the game?"
The reason was due to the fact that early in beta-testing, every weapon dropped by NPCs was fully loaded, and pretty soon testers found themselves drowning in ammo, and subsequently, the testers complained that Human Revolution was too easy.
When Eidos Montreal reduced the ammo drops, playtesters were forced to improvise. According to the developer, "We saw a lot more exploration and creative problem solving." After the initial complaints about the scarcity of ammo, people started enjoying themselves. "The fun factor went up. Drastically." Ultimately, "People started to ‘get’ what Deus Ex was about."
Deus Ex: Human Revolution will be released next week on August 23 on PC, Xbox 360, and PlayStation 3.