Many times I define a class and soon I will feel the design is bad, making the problem more complex. Sometimes I define a lot interfaces today and change all my minds tomorrow and re-write them all.
That problem won't really go away if you switch to pure C, though, except that you obviously won't be writing any classes. Instead you'll write a set of functions operating on a certain type of data and then change your mind the next day and rewrite them all.
So I want to know how does professional C programmer write their daily codes? For example, when a linked list is used to organize some data, will you directly operate the pointer to next node in the application's algorithm, or will make an abstraction to hide the details of linked list?
There are probably various third-party libraries available that provide somewhat generic data structures such as lists and so on. It's just that in C, "generic" usually means mucking around with void-Pointers and constantly casting to the type of data you're using the structure with.