I agree with this idea on principle, but feel it should go even further-as I've said in other posts!
Basically, instead of selecting SPECIFIC techs to research, you should instead have to break your science budget into broad tech categories, such as: 'Science', 'Commerce and Economics, 'Culture and Philosophy', 'Military', 'Industry and Infrastructure' and 'Naval and Exploration'.
The amount of your budget that you sink into each category will determine the approx. chance, and relative frequency, of discovering techs which fall into this category. The rub is that, like SMAC, what you actually discover within that category will be fairly random-though it will still be related to the era you are in AND whether you have any prerequisites for that tech! For instance, having a 'prerequisite' should no longer neccessarily prevent you from obtaining a particular tech-but HAVING one or, when appropriate, multiple 'prerequisites' will increase the chance of you getting that tech over another!
Other factors which would increase the chance of getting a tech from a particular category would be your civ characteristics-like militaristic, expansionist and the like. These characteristics would have a positive effect for researching certain tech categories, whilst having a negative effect on others! Cultural 'Flavours' might also have an influence on your chances of getting a particular tech, within a category, over another! For instance, whether you get monotheism or polytheism might depend on your civs 'cultural bent', as it were! Also, having a source of appropriate resource should also help in discovering a certain tech! For example, if you have managed to uncover a source of iron, then this should give you a bonus to your chances of discovering 'Iron Working', with the bonus being related to the size and number of the resource that you possess!
The last point is that, should you become aware of a specific tech, through diplomatic channels, for instance, then it should be possible to select that tech as the next one, in the appropriate category, that you wish to discover.
Yours,
Aussie_Lurker.