What makes you think there is a hell? Somebody tell you about it? If there is a hell, then it is the result of people's thoughts. Well, maybe not 'people' but the result of thought by something.
You can't love something you fear. It is an impossibility. Love God yet fear Him/Her/It. Can't be done. Fear, in all its manifestations it seems, is an absence of Love. So this business of 'Would people still love God if there wasn't a hell?' infers that one is forced to be good out of fear.
As William Shakespeare said, "The quality of mercy is not strained." Mercy, compassion, love - these are inherent. Once we begin to shed our fears our true self (which is infinite love, infinite joy and infinite compassion) comes out of its own accord.