If someone has spent the time and effort to code a product (for free) it's their choice whether they want to insert a copyright notice. You now have a choice, Use the product (copyright intact) or don't or as nexy stated pay for the unbranded version or ask the author if you make a small donation can you remove the copyright notice.
Personally, I would like to see 48pt sized copyright notices but thats just my preference.
Edit: I noticed this thread is in relation to this thread. If you take a look at the thread/product you complained about you'll see that the author stated "I depend on you. Also donations will help me to improve the product." So, make a small donation to him/her and he/she most likely allow the removal of the copyright.