Jesus is quoting as saying: "Happy is he that believes without seeing". I say: "Righteous is he that does good without believing. For if you do good expecting to be rewarded by God, or for fear of punishment, of what credit is it to you? Do not sinners also do good with the expectation of a reward, or to avoid punishment?"
You know that point JWs make about God allowing Job's integrity to be tested, so it can be seen if Job only served God because things were going well with him? Well I believe the point you're making actually raises an even bigger question about worshipers motives in serving God. How is it that Satan never challenged man's integrity on the grounds that humans are only obedient because they look forward to a future reward from God and/or to avoid future punishment/destruction? Isn't that a far bigger and more pertinent issue when it comes to human integrity. You would think that Satan would have addressed that first because the story of Job does not address it, for even while Job was suffering he was still looking forward to future reward for his faithfulness - the resurrection. (See Job 14)
The bible does not in any way address this issue. So what if a rebel accuses God of bribing and scaring humans to be good by promising them future reward or future destruction? How is god going to handle that issue transparently for all creation to see that such accusations are false? I think this is a major moral issue that the bible and JWs have overlooked.