Most of the modules involved are development side resources that don't end up included in the build. Complaining about the number of modules is like installing visual studio, noticing that it takes several gigs on disk and being like "Gigabytes, for a hello world program?"
But if you're using React you are creating a not-insignificant webapp and the initial install time of 177 modules is totally irrelevant beyond that first install. It doesn't have any reflection on the size of the client JS file (webpack loaders, for example, only live on the dev machine).
Moreover, you can presumably globally install this, so it can cover every React-based project you need to build.
It's just an example to show what type of code `reactpack` builds, ES6 and JSX with style loading in this case. If you want a more minimal React-like build you can switch out React with lightweight alternatives like Preact or React-lite.
For reference, I build a standalone datepicker module with preact + redux at under 20kb (min + gz)... worked out really well. By comparison, went with regular react recently, and the payload quickly got over 200kb, though I needed a couple relatively heavy libraries for the app in question.
Another point worth mentioning is using react-icons individually (svg based), same for component libraries where you are only using a few components... tends to work out much lighter. Also, if you do use bootstrap as a base css library, work from the source instead of monkey patching the .css output.