Hmm, MOO3 had that; it was somewhat interesting; maybe if it were incorporated into SE5 it would be even more interesting
MOO3 even had different randomized tech trees for each race, so the Humans might get Phasors at level 5 of Physics, the Klackons might get them at level 7, and the Ithkul might never get them at all, but might instead get something else...