Are we so sure it woud increase the chance? I could see two ways that NPC's get selected:
ALL NPC's have their own chance to occur, so like, a 12% chance of a Stryll Assassin. This seems unlikely to me, as every single time Dan added an NPC, he'd have to totally readjust all their percentages. On the other hand, this might be why new NPC's come out slower than molasses

My guess for how it's done though is that each *category* has its own percentage roll, so like, 70% chance of common, 20 % of uncommon, etc. (these numbers are TOTALLY MADE UP, by the way, don't quote me on them) Once the category's picked, the game selects a member of the class at random, and that's what you're fighting. There might still be weighting inside the class, to account for the fact that some seem rarer than others. In any case, if Dan added a new NPC, he'd only have to adjust the weights within the class, not the entire set.
In any case, if the selection method is the second one, getting rid of Data Analyzers wouldn't help find more troop carriers, just more Tech Collectors, Flamehawks, and Assassins.