I hear the same argument being levelled against 'drama' in other mediums, such as literature and television and I don't quite understand the complaints. If you manage to write fairly realistic characters who speak and think in a believable manner and use them to explore some of the most fundamental aspects of what it means to be human (in the case of Natsuyuki Rendezvous the aspect explored is clearly interpersonal relationships, specifically marriage and death) then I would consider that to be quite an accomplishment. I don't see why such material is uninteresting.
Fictional work is like a flood. The amount out there is more than one could ever conceivably sort through in their lifetime. Conceptually nothing about death or marriage is unique, so simply dealing with those in an environment that is otherwise familiar is simply dull to me.
Furthermore, trying to grapple with certain themes that pop up often in fiction doesn't require the uninteresting dialogue and flat minute to minute that
Rendezvous carries. I am going through The Wind-Up Bird Chronicle by Murakami right now which also focuses itself around marriage and death, but its handling of the material is stimulating and I find it able to provoke me on both a mental and an emotional level while maintaining possibly even a greater sense of realism than
Rendezvous.
Predictable, and carrying an air that seemed as though it had no enlightenment to offer I found myself unreached by
Rendezvous, and had no real incentive to pursue it. I suppose there is always the possibility I am missing out on something, but the first episode did not leave much of an impression.