The game's science system is laughably bad. Why do we have KSC science? What don't we know about the place we're around? How does landing on airless Minmus help researching aerodynamic stuff like wings?
If I were to implement it,
1. Instead of buying nodes with science points, you select a tech tree node as a focus, and R&D upgrades allow you to focus on more things.
2. Research on a specific node is done by using parts of the previous node (like "test part X in Y conditions" contracts).
3. Exposing parts to extreme conditions (with them surviving) is more rewarding.
4. Free-floating (point based) science yielded by sensors/samples/labs can be sold for good funds or invested into already reserved tech nodes to make the corresponding parts cheaper.