I've only read Thud once and enjoyed it but thought it was pretty 'flat' because
of the lack of humour. Whilst warring over 'people who are not like us' is part of human nature (in the broadest way possible - which is on
the Discworld) so is having a joke or a lark in even the darkest of times.
Biggest possible example - WW1 killed a million people on the battlefield, but Spanish 'bird' flu' killed as many as it struck immediately afterwards and killed as many women as men. This re-established the procreative balance and allowed the birth rate to recover relatively quickly once peace was established. BUT, in the UK the birth rate during
WW1 and WW2 actually rose drastically amongst the unmarried
population - why? Because death is scary and almost certain death doubly so. What do people do when they're scared? In Britain they went to the pub and the theatres (which hastily switched from dramas to musicals and burlesque/music hall style comedies) and had FUN. After the theatres and pubs chucked out they all went and had yet more fun of the carnal variety and during both wars a lot of kids were born without fathers either because they'd been killed or had only stuck around the one crucial night... The same thing happened on the continent in both World Wars of course, especially in places like Paris where soldiers went on furlough occasionally and did exactly the same kind of thing as they did before they left home in Berlin, or Birmingham, or Boston (Lancs or Mass). They went out and blew off a lot of steam and then got laid.
Life/Hope and Death/Fate double date
Anyway the debates between boys and girls in Thud are simply there to add light relief, absolutely in context
, except they're Tawnee and Nobby, not dwarves and trolls. When I hit bottom the other day I made a very off-colour and extremely cynical joke about suicide - deliberately laughing at 'death' (of hope in this case) is my way of coping with demons.
Terry's written this book in the same way as he wrote Small Gods and Jingo. The reason it's not as funny is because he was further down the maturity road and no longer needs to be as funny or just wanted to be funny in a different manner. That's all it is. Horses for courses.