I think for some (not all) people the hope of something more becomes a crutch and allows for laziness with regard to fulfilling a persons dreams. As in "I'll have a better life in the New System, or Heaven, or whatever. Heaven can be right now, it's all a matter of choices and determinations. And if it comes later, so much the better.
You know, not all major christian faiths believe in waiting until the here after to have a full life. The Anglican Via Media teaches that the earth is a good place. God made it after all according to them. We should enjoy the life we've been given as a gift, as fully as our health, mental and physical will allow.
If we live forever, we aren't going to think about forever. If you don't have the possibility of your life being cut short hanging over you, you aren't going to think about forever. You're going to think about your dreams and the things you want to accomplish. You're going to make plans to see those things to fruition, without a care or worry. You'll simply live and enjoy living.Forever is something that only matters to finite beings.
I don't believe death is God's plan or fault. We sure do learn from it though.