Edit: Additional: Forgot to answer the first question in my neverending quest to bore people silly with text walls. My score would probably be 2.5 or so. There needs to be changes, but nothing to massively sweeping or drastic.
Currently a lot of the techs are so intermingled (either with multiple requirements across the tree, or requirements within another tree) that it feels like you need to pretty much research everything anyway. It isn't so much a choice of which to research, but which to research -right now-. Something I loved about Galciv2's research is that it felt broad enough and disconnected with each other enough that you had to make a decision about how far down each individual tech you were willing to travel.
So overall my suggestions would be the following:
1. Seperate out the tech trees into the various important areas (examples below) and remove or limit the pre-reqs in other trees (e.g. Having to get Higher Education before being able to touch any of the more advanced weapons). While there can be shared roots (e.g. trading and economics having a shared opening tech)
2. Have a larger number of techs with more incremental bonus', with plenty of bonus' seperate from physical improvements like new weapons or buildings, so focusing in an area has immediate dividends and feels like a proper focus. For example, if your game as Trogs involves researching plenty of heavy armour and defensive techs and your game as Krax involves researching one handed melee weapons, even when the Trog and the Krax troops you design have the same armour the Trogs should have a higher defensive value.
3. Examples of important tech areas as follows
Society tech:
Research (improves overall research and grants research buildings)
Farming (improves overall food per grain and grants farm buildings)
Unrest limiting, production, mining improvements, trading, economics etc
Warfare tech:
Polearm weapons (improves baseline damage of polearm weapons and grants access to polearms)
Armour (Grants access to chainmail armour, then improves the defense and lessens the encumbrance of it)
One handed bladed weapons, all major weapon types having their own tree, formation size, army size, mounted combat, etc
Magic tech:
Recruitment (incremental bonus' in the level of heroes that can be recruited, including reducing the cost of recruitment and unlocking buildings that train heroes when left in a city)
Exploration (incremental bonus' in the level of quests that can be undertaken, and can be used to 'restock' quest areas by spawning a number of quest locations around one of your cities)
Magical items, unique units (Scion), unique magical spells, etc.
The idea is that rather than the tech tree being a path everyone stomps down, it becomes a choice where the player has to decide where they will focus their efforts. To compart once again to Galciv 2, it means there will once again be the question of "Which will I put more effort into getting, larger hull sizes, better weaponry, or better factories to make the ships faster?". Of course in any longer game the player will be able to research it all anyway, but in the mid-game at the moment it doesn't feel like I'm deciding what I'll focus on, just getting the next step in the chain.