There's nothing wrong with pre-hopped extract...it's like anything, it's not the ingredient, it's what you do with it that makes beer good or bad...following those instructions will make crappy beer...Doing the same "recipe" with everything we know about using sugar, temp control, sanitization, yeast handling, conditioning, can make really good beer.
One of the reasons we still have a homebrewing culture that didn't totally get wiped our by prohibition is because the smart breweries like PABST BLUE RIBBON made pre-hopped extract and sold it with cookbooks for baking that clearly stated on them, "
DO NOT DILLUTE THIS PRODUCT WITH 5 GALLONS OF WATER, BRING IT TO A BOIL WITH SOME SUGAR, COOL IT, PUT IT IN A CROCK AND SPRINKLE THE YEAST THAT JUST HAPPENS TO BE STUCK TO THE CAN, BOTTLE IT IN BROWN BOTTLES AND DRINK."
You need to THANK pre-hopped extract and the Blue Ribbon Malt Extract Company, for explicitly teaching us, though somewhat badly how not to make beer when it was illegal to do so.
Blue Ribbon Malt Extract is still being made, now by a Detroit Company called Premier Malt Extract. We have a thread on it
here....There's even a podcast link with one with Charlie Papazian, and a brewer that used to brew with it.... Fascinating history.