They're bugs. They should have some sort of hive building that boosts pop growth, and should have some sort of farm. They're freaking bugs!! They're ants out there that manage their own fungus farms, why wouldn't the thalians be capable of farming?
First off, they are
Insectoid, not actually insects. They have more in common with spiders than ants, if I remember correctly (at least that's what I gather from their appearance).
Second, they are capable of farming. Every race is, from the beginning. The Initial Colony produces 6 food, after all. However, I do agree they should get a farming line. Ones that also produce Morale would be just dandy.
On top of that, weak soldiering? They should be awesome soldiers. (starship troopers...)
Meh. They are nothing like the bugs in Starship Troopers.
Edit: And influence is their key to victory? My lord, that doesn't make any sense. Who is going to join up with bugs? It's like defecting to the Yor.
Where did you get that idea? The only reason the Thalan AI builds so many Embassies is because they are the earliest available planetary improvement after their three Galactic Achievements.
The Thalans could be incredibly strong in a Conquest Strategy, given the huge +Weapons bonus they can accumulate from their tech tree. Their Soldiering ability really isn't that weak, by the way. They have one tech that gives +30 Soldiering that isn't Tradeable, after all. Its just that their low population numbers and growth inhibits their ability to make soldiers. However, I typically keep the homeworld (since it has 24 billion max pop...) cranking out Transports and never really ran out of them at any point in the games I played the Thalans.
Was any thought put into this?
A lot. However, it was directed towards their role as "Time Travelers" rather than their "Insectoid" nature. What was done with the "Time Travelers" bit was very well done, though.