'Why does God allow suffering?'

It's a perfectly reasonable question, one that isn't negated by appeal to comparing a purported eternity of bliss to a temporary existence with suffering.

If I booked a cruise, at the beginning waited in a smelly departure lounge, complained to the staff about the odors, with them then explaining to me "don't worry, the departure lounge smells bad but the cruise ship itself is perfect!", it'd be perfectly reasonable for me to be highly suspicious of their claim.