Don't get me wrong, I'm always down for more gamerscore but if the price of the games goes up too much then I will definitely be thinking twice before buying an arcade game.
New XBLA Achievement Rules
Here's a look at the old rules for the XBLA (stolen from x360a):
OLD RULES
Base: 200 Gamerscore / Max of 20 Achievements
DLC: Up to 50 Gamerscore + 5 Achievements per Quarter (3 Max)
Total: Up to 350 Gamerscore / 35 Achievements
And now here's the new rules for the XBLA (also stolen from x360a):
NEW RULES
Base: 400 Gamerscore / Max of 30 Achievements
DLC: Up to 100 Gamerscore + 8 Achievements per Quarter (4 Max)
Total: Up to 800 Gamerscore / 62 Achievements
I guess only time will tell, but I don't see any games worth 400 gamerscore being 400 points or less...