First, Russia is not weak if you play them right. All Civs are strong if you play them right. That was the initial intention of Sid Meier who claimed that all Civs should feel "overpowered".
They are, despite my own statement that they "can be" powerful. And here is why, at the start Russian plains are no different than grasslands, so there is no benefit for spaces worked. Only after a city has granary is a plain much better. Compare that to Japan who will work sea spaces anyway for trade but will get a bonus food alongside the normal value.
In other words, there is no good reason to work plains prior to granary production.
So Russia will place granary as a higher priority? Great, how soon will that early production pay off, even just using it on a one-on-one basis (one hammer = one food) its many turns for it to pay back.
Then considering you are usually sacrificing food for early production, you've actually lost some growth by building the early granary.
Its still best to just get the free granaries at 1000g, but to make that most effective you want to have 3-5 cities when you reach it so you are focusing on growth and settlers. And thus you are settling around good food resources with few hammers (forests for early game). So where does that leave the 1 food plain cities?
In a sense you have to follow an early non-optimal path to fully realize the potential of the Russians.
Secondly, I hear you and others saying that it is silly with half cost spy.
They are cheap to rush, assuming you are playing a typical strong strategy. More specifically, you have couple strong gold cities with markets and banks and maybe merchants, you should be getting 300-1000 gold per turn which you can easily rush a few spys when needed. Unless you are facing a ring in the city (in which case I would just not bother with spys) you can usually just throw a few veterans at the city and eventually win out. A single ring is mostly all you need otherwise, and then a spy rushed anywhere (non-vet) to get the GP or destroy fortifications.
Since you can at best have a vet spy ring, and you have no way of knowing what the enemy may have in their cities its always a guessing game. Is it worth the effort to build a spy ring only to have that lose to (by its very nature) a heavily fortified spy ring in an enemy city? I find its not, although around mid game I do attempt a spy ring rush and attempt to round up all the AI GP, but once my spys die I give up on that strategy. I use one spy ring to test the waters or kill the enemy (then leave) and then an expendable spy to get the GP. I do this as long as the spy ring lasts.
Although, if I don't have a large tech lead and the game isn't almost done I will easily expend as much resources as is needed to get a great leader.
There are possibilities for games versus humans, but the non-optimal path Russia would have to follow would preclude a late game advantage because you've already been destroyed by the early game weakness.
An all Russian game might be fun with other humans, but that doesn't seem possible, and I've not been able to play any network games anyway.