Wow. That is awesome. I assume that the reason is that art of that quality is epensive, haha. Plus when you have good cohesive art, it tends to all be by one person. That isn't the case in a card game. You can't go for bang up art like that and then ask the next artist to draw a similarly good card with Gabriel in it. It just couldn't match the quality.
It's not just the quality but the consistency. The Gabe of the LCG is not the same as that of Infiltration; his appearance changed.
You don't need to have the same artist for that; that's why companies dealing with persistent characters and continuing storylines produce art designs and style guides so that even if different artists deal with the same subject, they remain true to what was established.
What's weird here is that Gabe's A:NR ID changed from Infiltration's but his original appearance is in Bank Job. Compare that to Mac's ID and Modded, or to Chaos Theory and Big Brother. Lots of quotes in the game are also references to other parts of the Android universe.