I’ve spent many hours thinking about tech tree representation. The AoM in-game tech tree - not my preferred style and not the prettiest, but the current implementation in AoE3DE is barely usable, and replacing with the AoM style will be an unambiguous improvement.
You also overlooked a potential benefit: all our in-game tech trees outside AoE4, including AoM itself, have been handwritten. Writing these has been a laborious, error-prone process. The AoM style is simple enough it can be auto-generated, at least in theory. All we need is a generator that knows how to parse AoE3’s titan-sized cobwebs of tech prerequisites with all the “same unit, different proto” and “different units, same proto” hijinks
The auto-parsing gets even harder, if the tech trees also must show (and denote!) options unlocked by shipments AND units only available via shipments, which it absolutely should, as many of these are essential. You can’t have an Ottoman tech tree that doesn’t show Spahi.
Aesthetically, whether generated or handwritten, your results will look uglier than AoM. Techs in AoM are fairly regularly distributed over the ages, giving your example a clean “rows of items divided by category & age” layout. AoE3 is a lot messier, with many “breaks” and single-age clusters:
A dozen Church techs, mostly in Age 2;
14 Arsenal techs clustered in Age 2 or 3;
Factory options in Age 4 & 5;
Econ techs are broken up and scattered into Market, Dock, Mill, Estate, and Capitol/TC;
9 Capitol techs in Age 5.
That’s not counting the current AoE3DE’s messiest part, the bunch of Tavern units in every tech tree . Those really should have been two simple icons: “Recruit (Standard) Outlaws”, “Recruit (Standard) Mercenaries”, clicking on which will pop up respective encyclopedia pages: list of random mercenaries, and list of map outlaws.
Speaking of that, I feel AoE3DE definitely can use a hypertext encyclopedia UI that displays useful gameplay info, available during gameplay. Ideally also functioning as a unit builder. But with AoE3DE, memory footprint might be an issue.
There’s the Mexican revolution chain. AoE3 also has units that upgrade in the same age they unlock (Mortar and Horse Artillery), and the Capitol’s Knighthood->Peerage tech. But yeah, these are minor exceptions.
Yes, I’ve thought about that too. In my own UI proposal document, tech trees are handwritten (for aesthetics), but card groups are generated, since they are all equal-ranked and in 5x4 groups (except for a few new cards that replace themselves).