I'm all for experimentation. All but one beer I've brewed have been from my own recipes. With that said, I did my research first. Before even making my first batch I read everything I could about the brewing process and about two years worth of back issues from BYO. I made sure I understood everything I could about the process before beginning. But that's just how I am with any undertaking. I think one of the main problems with new ones throwing all kinds of stuff in their beer is they don't understand what the finished flavor will be. I've never brewed from a kit, but I see nothing wrong with it and they are proven recipes. But there's a reason why each kit contains the ingredients it does and not an option for cherries, brown sugar, etc. If you want a fruit beer plan on a fruit beer. Adding fruit or spices or sugar or extra malt extract might not work with the base beer you're making. Planning ahead goes a long way to helping make good beer that can be repeated if you like it. I just think those who are posting in this thread just want to help new ones not make the same old mistakes time and time again and then wonder why their beer is bad.
In summary, do I think it's a good idea for someone's first or second batch to be an imperial chocolate cherry molasses ginger hefe coffee stout? No
Do I care what you brew with your own equipment, time and money? No