Yeah... I suppose that could work. But you are going to have to crank the kobold black market up to 11 to really balance things out for them.
Balance is overrated. Kobolds are more appealing as underdogs who are curious enough to try anything but suck at everything besides hiding in caves and collecting bugs (with exceptions, of course). It would be hilarious to see their confused attempts at trade.
Underdogs is fine. I don't have a problem with that, but they should still be excellent at some things, or else they shouldn't be a Civ.
We can get a lot more use out of them than just mining them for comic relief. And just because they're fairly primitive, small, etc. in no way equates to their being unintelligent.
They might be masters at trading, for that matter, since they'd have to use the barter system, instead of coins, and since they're thieves.
I mean, let the leechmen or the batmen or the skunkmen or whatever be the total schleps.
And even *they* should have a few things they individually-as a sentient species-excell at (for instance, I'm really very fond of the idea that Leechmen have medical skills/abilities that trump everyone else's, and antmen could be a lot more developed in the game, possibly having their own aphid "honey" to trade.).
Kobolds I'd really like to see be representative of an "aboriginal" people who were in these lands before everyone else, and who may be looked down upon, but have their own lore, culture, and ways of doing things, that sometimes will be awesome.
Bug lore could be a part of that.
For that matter, the landscape could be dotted with kobold ruins, and kobold burial grounds.
The fact that kobolds are probably not good soldiers is enough to make them underdogs. It doesn't mean they have to be lame in all other ways.
I'm not saying that that's the way things have to be, I'm just saying if it isn't, then I hope it'll be replaced with something better/deeper.