Because having someone swoop in and magically fix the tech is boring. And really, if that's going to be the solution to all the problems on the show there's no reason not to have one of the regulars like Eli or Rush do it.If Chloe is so useless, why isn't Colonel Carter or somebody more qualified body-swapping with her in this time of crisis?
Sacrificing an obvious technical solution for the sake of cheap drama (or giving your regulars something to do) only means the writers didn't have any foresight.
Oh come on, you could make that complaint about every spin-off in existence. Spin-offs simply can't go calling in the main characters of their parent/child show every time there's a problem.
Why didn't Buffy call in Angel for help fighting Glory?
Why didn't Angel call in Willow to try some magic on the physically indestructible beast?
Why wasn't the most powerful ship in Starfleet not in any major battles against the Dominion?
Why was Sisko not captaining the Defiant during the Borg battle?
Why is Garbielle writing a play while Dahak, in Iolaus' body, is destroying Greece?
Why was Cliff's retirement party at a bar in Boston not held at Cheers?