I love the idea of a code snippets library. Apart from anything else, it would help significantly with support queries because so often the answer to such queries is to add a snippet of code. Having a central repository of such snippets means (a) some people will search them first and, perhaps, find the answer to their query without having to ask and (b) those responding to a query can simply link to a snippet instead of having to write it from scratch each time.
I do, however, agree that this should not be in place of a plugins directory. The truth is that plugins and snippets both have their place, and they are useful in different contexts.
As for this comment:
After that 10 base plugin plus 5-10 business plugins I notice that the admin interface works slower and slower.
That is almost certainly not a reflection of the number of plugins being run. I have run sites with over 80 plugins installed and seen hardly any impact on site speed. The issue you are witnessing is due, I suspect, to at least some of those plugins containing code that is not particularly well written.
That’s one problem that ClassicPress inevitably inherits from WordPress. The relative simplicity of creating, making available, and installing plugins makes it easy to use poorly-coded plugins. That is not an issue resolved by turning those plugins into snippets. It can be resolved only by improving the quality of the code used.