No, it is not that simple in practice. There are a variety of security related details that will need to be handled. It is not extremely difficult once the initial network is proven, but will still take some work to ensure no data leaks.
Computation will always involve some type of language. You are describing what has been considered the most basic form of general computation on the network. We’re talking about the same thing. A network node doesn’t need to support all kinds of different plugins, just a single computation feature or shell (ex. safe + bash = sash, the safe again shell) that can take a file and perform operations dictated by the file in a safe manner on a set of nodes without leaking data while using group consensus for error checking. Specialized apps can then use this general feature to accomplish everything you are describing (Weather, Voting, BTC transactions, etc). The core stays simple and minimalist. The possibilities for apps remain limitless.