Well, remember that the Ages are an abstraction for many detailed restrictions. From a game-balance perspective, your actual choices are the following two:
- A simple tech tree, with Ages
- A tech graph, with wide branching factor, many more dependencies, and rules (but no Ages)
You can't just discard the Ages and keep the same simple tree. That's surely broken, and the tree was never designed to allow it.
It sounds like you'd be willing to accept option #2, and just play on the complex graph. (I might be interested in that myself!) Then you could probe all kinds of unbalanced strategies. Chess calls these "gambits" or unsound piece sacs, and yah they can win if the other guy blinks. However, balancing that well is a game-design nightmare. Given that Stardock is already swamped with dev work for 7+ months (and 7+ years after official release), I don't blame them for making a director's-level judgment call that they shall appeal to the masses first, and fry bigger fish.
Remember that most players aren't us. Less hardcore players would probably just be lost in a graph. Your Diplomacy-heavy strategy already reflects some expertise in knowing all tech paths, and calculating that you can outrace them all anyways. Let's not appeal from our expertise that we need more help to make us even more expert than the noobs.
Finally, keep in mind that Paul has GC3 DLCs mapped out to 2021(!!). Surely within GC3's loooooong lifespan, somebody (maybe Stardock themselves) will publish an Ageless variant with the hardcore tech graph, and it'll be pretty well balanced (or converge to it). It's not so hard to envision: just make yourself a nifty graph-based UI, bang out all of the links between techs, maybe add a couple of game engine hooks to apply penalty policies, and let players gamble on gambits. I would love to see (or invent) that myself: then we can drag the 4X community across an epochal boundary, from the Epoch of Trees to the Era of Graphs. Then we'll branch out into RPGs (you level-up to advance in a skill graph), 3D modeling (boundary representation is a graph ), and web forum badges (you must earn points in multiple sub-forums to advance up a badge graph). It'll blow adults' minds (when all kids know this).
For GC3 initial release, though ... the Ages mechanism is probably set in stone. If you judge it on its (apparent) design goals of:
- being simple to grasp (for newbies and broad market appeal);
- simplifying (abstracting) the graph to a tree; and
- enabling customization (of races)
then it really is quite an elegant mechanism. (Corollary: Your arguments based on gameplay alone have just been trumped by the Marketing Department. Grin and bear it, it's happened to most of us.)