unlike other SPs that immediately grant massive benefits WP requires a lot of former turns to start paying itself off after you've invested 200 minerals upfront.
We're probably calculating it differently.
Each former is 20m, WP makes them twice as fast. If you need 1 former per base, with WP you save an equivalent of 10m per base in construction cost and 0.5m/base/turn in support.
Even with 5 bases you save 50m+2.5*turns or ROI ~1.6%/turn. With 10 bases it's 5%/turn.
You also get tempo (faster tform means less pop/crawler turns lost on unupgraded plots) and can do aggressive speed tforming potentially cheaper. And I haven't even considered better terraforming.
Compare it to Merchant Exchange that gives 0.5m/pop/turn or 2.5-3m/turn pre crawlers and energy upgrades or ROI ~1.5%/turn.
Considering that you basically have to ICS, WP has significantly more ROI than other early projects (HGP gives ~1m/turn/base, CDF and CC are more situational, TVW is great but it's a bit later one).
I guess, I don't play enough competitive MP to value CC and CDF properly. I don't remember needing 6+ bases churning units nonstop to make CC worthwhile vs AI.
Weather Paradigm is +50% former speed, not +100%. Faster terraforming also means you spend more time running around and losing former turns to get to places, so that balances out. If you have 1 terraformer per base it's +10 minerals immediate worth of former value and +0.5m/turn in support for each base. Let's say 20 bases, which means it pays itself off immediately (200 minerals saved) and thenceforth "earns" you 10 minerals/turn in saved mineral upkeep.
Merchant Exchange is a famously awful special project that no one should care about for normal gameplay. Let's ignore that.
Human Genome Project: Replaces a Rec Commons at every base. This costs 40 minerals/base for an immediate gain of 800 minerals worth of infrastructure at 20 bases, along with saving 1 energy/turn in upkeep which for 20 bases is 20 energy/turn. Now, you can directly buy 1 mineral with 2 energy so this can be converted into 10 minerals/turn in a much better and more flexible way than base minerals can. So we're looking at 4x the immediate payoff and the same per-turn payoff.
Note: exactly how much HGP saves can depend on what you avoid building, if all you would have needed was 1 police then it obviously saves a lot less, 10m/per base and 1 mineral upkeep/base for a total of 200 minerals and 10 minerals/turn. Which... is exactly the same as WP. If you would have needed later more expensive buildings then its even more powerful than I calculated before. I chose rec commons because its a fairly common early game building you need on transcend.
Virtual World: Costs 300, replaces hologram theaters costing 60/each with 3 upkeep, so 1200 immediate mineral saves and 60 energy/turn, convertable into 30 minerals/turn. Turns out to be similar ratios as HGP, though it has the downside of the fact that you don't often need this much drone suppression everywhere and you need to build the network nodes.
Planetary Energy Grid: Costs 300, gives an energy bank costing 80/each with 1 upkeep. 2400 mineral savings and 20 energy/turn. And unlike the other two you do kind of want energy banks literally everywhere.
Keep in mind, ALL of these SPs are amazingly useful once you have tons of bases. The problem is that they require a huge initial investment that you can't pool all of those base's mineral income to rush (until supply crawlers). Which means you're risking a lot of immediate time to go for one, and as I've said on transcend it seems usually not worth it (though you can disband non-supply crawlers for half their construction cost towards the project, I'll have to try using that to rush SPs sometime...)
On the other hand, impact rover spam is something you CAN dedicate all of your 20 bases towards, and quickly skyrockets you to having 30 bases and a nice SP along with it. The only problem is if all the good SPs are magically finised by some AI on the other side of the world. But at long as 1 or 2 decent ones are nearby you can take it and adjust your plan to fit with what you get.
As to WPs early unlocking of terraforming, it's kind of hit or miss. Really depends on your resources, since condensor farms are only particularly good on food resources while boreholes need minerals or energy resources and also take a ton of time to finish.
