As others have stated; No trust exists for an armed, mechanical thing that may or may not turn upon it's makers. Watch the original Robocop;
The ED-209's are a prime example of why we should never trust machines to have decision-making capabilities and have the task of ever killing anyone.The day a mere A.I ,however advanced, is entrusted to attack only certain humans, but not all, is the day of a disaster in the making!
The Power Armor of Rifts earth is the best way around the extremely expensive, extremely dangerous, and unreliable A.I. question/problem.
As to modern warfare/WW II and Rifts Earth; The real world American Coalition (Doh!) still has real problems with tanks in a city (or a forest for that matter) that the WW II forbears had to face. The near-immobility of a tank (or similar vehicle) in tight quarters was,is and always shall be a fatal liability of these machines. As to the Rifts Earth environment, the regular infantry is far from obsolete!
The Rifts Earth infantry has unprecedented armor, firepower and overall survivability. How can I say that? 3 reasons;
1)The Rifts Earth infantry can survive a single
anti-tank attack/hit!
Also on the list of survivable attacks is radiation, biological, and chemical attacks because most infantry have EBA suits.
2)The Rifts Earth infantry now carries weapons which can inflict as much as 1D6(X 10)MDC per attack (Blast or Burst)!
3)The Rifts Earth infantry now includes infantry type not available in the real world:Juicers (even "mere" Base Book types are quite deadly), Borgs Power Armor pilots and Crazies. All these are much more likely to survive a conflict compared to real world (and SDC Game World) soldiers.
These are my reasons. I realize that in a world of ultra-tech, the near invicibility of near perfect hunter-killer drones is a given. It is actually a good reason
not to make them. It would be just too dangerous should the drones ever go rogue, or are co-opted by an enemy. The Power Armor soldier is still imperfect; Still makes mistakes, still can turn traitor and miss more often than not:These are bad, but at least the turned soldier can be stopped by his own people. Near perfect rogue drones would cause far, far more damage/casualties than the soldier. Let's hear it for the good old G.I. !
To those who have risked/given their own lives for thier comrades, buddies or John Q. Public; Thank you! A million thanks are not enough for your sacrifices!