I use the buttons, and there are pros and cons to using them. The punches are faster, but are not nearly as powerful as they are when you use the analog.
I use the buttons because my style is more defensive, and I throw a lot of counters, and the buttons are a lot quicker.
And NO, the game was not meant to play with the analog sticks, its just a preference. Just like the view in NBA 2K, I still use the 2K view like the old Dreamcast games, its not an advantage, its just how I like it.
Step your Fight Night game up !