agree, such system's must not be free, and 2,5 usd... sorry, guys it's price of cup of coffee, if you developing something for you- you get free access, if you developing something for business (startup)- so, will you work for free in future? no, this people (developers) also need income.
However, only one what is not good- quantity of free project, limited to one, this could be a problem, because now you have a good feedback about lags and realized project's - it's free to try several hardware platform, and get some results. In case of limitation- developer will stack on polishing of one application, and payable customers will start to tell you " i pay- you must do it!"- it's psychology, nothing more. My proposal is to allow at least 3 project, may be with limitation to Arduinio/Raspberry/ESP ( but not limited)