and I can truly see why. It is comforting and calming and gives hope to those who suffer losses and/or don't feel fulfilled in THIS life....etc.

That's likely true for some people, Bill, but a lot of folks I know who believe in rebirth are neither comforted or calmed by the idea. Many (if not most) are just DYING -- quite literally -- to get off this earthly roller coaster, so to speak. To be free of the cycle of death and rebirth in this "vale of tears" and "graduate" to a life in the realm of spirit.

Most Buddhist teachings, for example, are directed to this end - not about how to celebrate or enjoy or enhance physical life, but how to get beyond, transcend, overcome it.

But whether or not we are restricted to one lifetime or free to have as many as we like, I don't think physicality is any sort of shackle to be wrenched off and tossed aside. Physical life is a privilege, a pleasure, an adventure, a learning experience without parallel. Those who think otherwise are missing the point of the whole exercise imo.   

Besides, according to most religious/spiritual traditions aren't we all supposed to have originated in the 'realms of spirit'? And if that's the case, what's the big deal about getting back there as fast as possible? We must have had plently of good reasons to choose to leave such a (purportedly) perfect existence. There must be many, many pleasures and benefits and experiences available 'here' that are not available 'there'.

Why else would we come? Would you opt to leave a beautiful comfortable home in say, Hawaii, in favour of struggling through some miserably difficult existence at the North Pole or in the middle of the Gobe Desert?