Re-rolling tech trees is purely random, but one of the things I like about the game is that it is primarily deterministic. What if researching a technology let you increase the chance it was rolled on that planet?
For example if you gave a +1% chance per rank then a player with 15 ranks in Volcanic Batteries could choose to increase the chance of rolling it on that planet from 25% to 40%, dropping the chances for Intergalactic Envoy/Heat Recovery/Catalyzer Technology to 20% each.
