The Tezos baking economics is based on a target of 100% baking. Yet, if a unit of tezos is baking, this unit cannot (as far as I can see), be used in standing orders for trade. This is, I either have my tezos in my wallet, or in a trading account (e.g. Kraken). I can only bake with the former, but I can only trade with the latter. For instance, you can see here, in the column headed "Grouping", a set of standing orders of buyers and sellers (the actual list and volumes is much much bigger; if you have an account with them you can see that). These are all tezos not being used for baking. Yet, they create the market for tezos!
So, baking and market-creation are incompatible activities. This might be a "problem" inherent to Proof-of-Stake models. Is this actually a problem? Does it undermine the tradability/liquidity of the coin, as people have incentives to have their tezos engaged in baking? Perhaps a few big players have more market power to manipulate the exchange rate?