Ender's Game vs Starship troopers

I've been rereading the Ender's game books recently.  Perhaps these are books that I just can't experience the same way twice, but I'm enjoying them a lot less this time.  I'm quite familiar with the overall plot line now, so on reading it again I'm focusing more on smaller details and smaller subplots.  And there's only so much that I can read science fiction sermons on the glory of monogamy, the mysteries of marital oneness, the nature of God, and the speculative arrangement of Mormon cosmology into science before my head feels like its going to explode.  Card has written a unique universe and I can appreciate that.  I think he deserved the hugo/nebula awards he won for speaker for the dead and Ender's Game.  But Card is first an LDS fiction writer, second a science fiction author.  I'd like to highlight large selections of text and write in the margin "And now we interrupt this regularly scheduled plot line for a special report on why wives should be subservient to their husband's" or fill in the blank for whatever he is sermonizing on today.  Its led me to think why this bothered me so much despite having loved Starship Troopers which by any measure is a preachy book.  I mean, the main character in Starship Troopers spends a lot of time describing his childhood participating in government mandated ethics classes.  And frankly, Heinlein has a lot to preach about where I don't think he's even in the same ballpark as the truth.

I think part of the difference is that in Card a lot of the plot tension comes from overly contrived absurdities such as:

• a sentient microscopic disease body, 
• the proposition that one shipload of pre industrial aliens can wipe out the whole human race when presumably most of the inhabited planets they might try to destroy would shoot them down before they'd ever get near enough to land or deposit their viral payload, 
• a virus that can wipe out the whole human race yet one isolated biologist in a backwoods community, limited facilities, and no networked system of fellow researchers can develop a bacterial antidote capable of eliminating the virus from a whole planet without undue difficulty
• A husband whose body will dissolve if his wife isn't more cuddly and nice
• An instinctive science search for ways to survive that involve killing as many people as possible instead of as few as possible
• local sewer systems which are controlled by an interstellar computer network, that can be run independently without difficulty but only if the connection to the instarstellar network is blown to bits

Heinlein has a lot of moral tension as well and some of it is probably contrived.  However, I don't recall feeling any of it is being forced into black and white categories that don't fit them even remotely.  Heinlein also feels like someone I can have a good argument with-wheras since Card is more preaching than arguing so I can't have an argument with him about where's he's right and wrong.  He's not inviting argument.  So far, I prefer Heinlein to Card.