A proposal. 

Core tech is available to almost everyone, and is researchable via the mundane acquisition of research points.  The acquisition on all other non-core tech  is linked to player’s action, which representing competitive edge and the strategic decision of the gamer.

Situational Tech
The requirement of getting those non-core is different for different tech, think the Wonder system in CIV4.  But the CIV4 is only one of the ways.  Some requirement can be pre-designed (e.g. getting the best non-magical Plate Armour IV requires you that no other armour type are produced in previous 30 turns).   All non-core tech has a pool of pre-designed requirements to randomly drawn from, so the gamer experience is different in each game you play.  Some times you have tougher requirement, some time you have easier ones for the same tech.
 
Some other  non-core tech requirements can be linked to a random quest generating system (if there is one, I hope), especially higher level tech.   For example, kill 5 opposing heroes & spend the research points, you’ll get the Cruel Hero’s Tavern technology.  In another game for the same tech, it can be explore 5 dungeons

Tech Branching
When I have already specialized in producing high level of Plate Armour IV,  a non-core tech, my cost to try researching Masterpiece Leather Armour IV will skyrocket (assuming archers can only wear leather armour)     My point is,  when gamer specialize in a particular stream of research, all other streams in the same related field become harder to research due to substantially increased research cost (and requirement).   In this game, I am very efficient in farming 2 type of crops because I have achieved high level of tech specialization of these 2 crops already.  It will then unlikely that I start researching a  3rd  crop type because the cost to research the level II of 3rd crop become very cost-inefficient for me.   This system force player to decide what non-core to get, what to let-go.   I will research the cost-prohibitive 3rd crop level II tech, only if I suddenly discover 20 more 3rd crop in map.   There is opportunity cost in picking one  non-core tech over the other.   

Moreover,  for some core tech, once you finished pick one field (a bad example Farming), it become impossible for you to get into another (e.g. Animal Husbandy).  Some tech will be disabled because you have previously chosen  to learn  another tech.

Non-core tech does not further branch out to other techs.  They are dead-end techs.  This means you only need to research all the core-techs to have a chance to attain all non-core tech.

Pre-game Option: Random (Bonus) Tech
I do not like random tech  in traditional stance. I will instead like the following:

There  is a pool of non-so-balanced/very powerful/game changing bonus techs that will not be normally found in the tech tree.   Gamer can pick one of this bonus tech before the game starts.  Alternatively, in some games he cannot pick the tech directly.  Randomly 0 to 1 of the bonus tech will show up in the tech tree at turn 1.   The gamer will have an element of tech surprise in almost every game, but still he needs to think hard on how best to use/when to research this bonus tech.

Presentation

I like a tech tree presentation similar to CIV4, a big map showing how & the situational requirement to get any tech.  

The tech tree will be partially visible at turn 1, showing only the techs relevant to the current "Age" only.  Later, when you research enough tech for the Bronze Age (e.g.) you are in, the tech tree will unhide all the techs in the coming "Renassanice Age".  The tech tree will produce an element of surprise, but still allowing you to plan your tech action for the coming 40 turns.

I don’t mean the tech tree is the same in the every game you play.  The non-core situational tech requirement will be different each time you start a game.  Faction affects how or what tech you can research.  Also, if you have experienced a Bonus tech from your opponent, you'll have a high chance researching the same tech, when your Next Age comes.

Infinite Tech
Most tech should have unlimited levels.  In turn 1, the tech tree only shows the first few levels of the tech, in the form of a “stack”.  Once you’ve researched all these lower levels, the game will generate a substantially higher requirement to research the next levels (& so on).   The benefit of new levels should balanced to the # of turn has been past,  so the benefit will never become irrelevant.   Also the situational  requirement and benefit will be generated according to a pre-designed formula.

The purpose of infinite tech is not exactly catering to a never-ending game.  For me, it is more desirable if your early tech remains useful IF you consistently putting research into it thoroughout the game.   For example, I’ll like to see Farming X is almost as useful to a late tech Refrigeration I.

Pre-game Option:  Tech vs Magic book picks
In MOM, you allocate spell books to make certain colour of magic stronger or weaker when you design your race.   Now in EWOM’s pre-game screen, you have say 20 books and you’ll need to allocate the book picks amongst Spell research AND Tech research.   If you put a lot of books in to Population related tech, you will be certainly weaker/slower in other aspect of spell and  tech research.

There should be an option to randomize, or choose a default set of book pick.

In some games, you may have powerful technology; in some other games you may have more powerful spells.  Tech & Spell research will then become one of the variables on how you customize your game.

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At the end of game,  what player has researched will be hugely different because they made the judgement of what non-core tech to specialize.  The gamer's faction, starting location, nearby opponent's choice/action,   will affect what non-core he choose to research.   He cannot research all tech, no matter how big his empire is.