Keep in mind that the best premium apps have lifetime revenues in the low tens of millions, and the best F2P are in the billions.
i.e. if 1% of apps are making billions but the other 99% are complete flops, it seems ludicrous that anybody would try to enter the market as this stage.
The inverse of this is likely just as true, sales are not made due to there being no free trial so someone just doesn't bother with it at all.
The solution that Nintendo stumbled on is to limit the number of uses to a demo, after which the demo is no longer playable. Unfortunately, this would require absolute cooperation from the app store, be decried as a terrible practice by many, and be moot on rooted phones.
There's a lot of games out there, and most of them are just cranked out rehashes or predictable and dull.
The problem with strategy is that your whales only pay once, even if they would be happy by paying thousands of times.