By having different skills, the player is forced to choose how they want to develop their character. It should give every player a different experience and make Deus Ex playable numerous times. Another player might choose to focus on computer and electronic skills, hack into an enemy's system, and sneak in right under their nose. The skills are not the only way to make each character original. The player's inventory will also make a difference in how the game is played.
Guns are nice, but they get heavy quickly and take up a lot of space.
Lock picking equipment, on the other hand, may not do as much damage but is much easier to tote around. You can see the numerous possibilities this will present during the game. These choices are largely what is taking the longest for the Ion Storm team to balance. They want to assure each route the player may take is both possible and fun. The NPCs in Deus Ex promise to be some of the most realistic ever in a game.