Even if we take the rather spurious simplification that all saturated fat = bad for you and all unsaturated fat = good for you, palm oil (~51% saturated) is still better for you than butterfat ( 66% saturated), about equal to beef tallow (53%), but worse than lard (41%). Although, lard has gotten a bad rap in recent years. Plus, it's practically indispensable in a good pie crust. But I digress.
Source:
http://www.uccs.edu/Documents/danderso/fats_oils.pdfAside from the fact that nutrition is more complicated than that - so I maintain - we are left with a couple of things to consider. First, in poor countries, any long term deleterious effects of consuming a diet high in saturated fats are probably outweighed by the simple need to consume calories from any sources. Is making a healthier oil really so important? So many other more pressing threats to health in developing countries - heart disease seems inconsequential at this stage. It's already hard to get critical drugs to such area, due to logistics and superstitions... imagine trying to get modified food oils, and educating people about why it's good to use them. A minor point is that poor countries tend to be in hot climates, and unsaturated fats have lower shelf life in hot climates. Finally, using hydrogenation to modify food oils for various reasons sounds pretty good at first glance, but it has the unfortunate consequence of generating trans-isomers in unsaturated fats, which are certainly far worse for you than good old "natural" saturated fats. Sometimes it's better off to leave well enough alone.
As a random aside, but not totally irrelevant Enthalpy since you mentioned making pastry with liquid oils, I have a great pastry crust made from olive oil that I like to use when I make quiches. Granted, sometimes you can't beat butter and lard (50:50 mix, no other option, although vegetable shortening works rather well too - and yes that's the only time I'll use it) in a pie crust, but for a healthier option, it's pretty good and you don't feel so bad about yourself afterwards. For that matter, I also use oil when making grilled cheese, and there I can hardly tell the difference.
Well, that's some random rambling on the topic from me.