The amount of the coins that are generated by staking at each block doesn't (directly) depend on the number of addresses that are staking.
Function GetProofOfStakeReward depends on the coin age (probably age of the coins in the user's wallet) and doesn't depend on the total number of coins (or addresses) that are staking.
It depends on individual transactions (and their value) and the coin age. If someone is staking then a minimum cycle is 8 hours so someone could lets say deposit 1000 into their wallet and approximately 8 hours later:
They get 0.01 interest (this is purely an example value to simplify this explanation) and such get returned 2 new transactions. One of which is for 500, the other for 500.01.
Approximately 8 hours later:
The previous transaction for 500 splits and returns one transaction for 250, one transaction for 250.005
The previous transaction for 500.01 splits and returns one transaction for 250, one transaction for 250.0125
At this stage, one initial deposit has become 4 transactions and this process keeps repeating at approximately 8 hour intervals if a wallet is left open for staking. On the next cycle there are 8 transactions, then 16, then 32, then 64. etc.
What exactly don't you grasp about this concept?
Yes, I know that the lack of transactions in blocks doesn't necessarily mean that there is anything wrong from the technical standpoint.
But if there are no technical problems, then there may be some "human" problem. I've just checked latest blocks and they still don't have any normal transactions (just coinbase transaction + PoS transaction). Why people don't move at least some coins around?
A huge proportion of the coins are at Bittrex as has already been highlighted by one of my previous posts. People just like to keep coins there for trading I guess. What do you propose? Maybe Bittrex should force them to withdraw to their own wallet just to satisfy your need to see transactions moving?
NOTE: I personally think it's a bad thing that so many coins are on Bittrex. People obviously learned nothing from the VRC/Mintpal debacle. They should really keep their coins in their own wallet until such times as they want to trade them.See my example at the top. If stakers don't clean house every now and then by reconstituting all those transactions into larger values then they can end up staking very often. They will only be creating very tiny fractions of new coin as the amount you receive is proportional to the amount of the transaction being staked. There is however the bonus that they may catch some fees at regular intervals if they stake often.