Alchemists are a hybrid of Wizards and Thieves, which makes them perhaps the least useful type in the game. Regardless, they may be more desirable than Illusionists because they can get your Wizardspell and Thief needs out of the way without being redundant with a Cleric. Still, utility magic isn't very good, and Alchemists don't have the gear to support a front-line role to disarm traps.