Well, that's part of the problem. I enjoy playing a great variety of decks, most of which are plenty good against a variety of plant decks. But berry decks are good enough against so many types of decks that they need a pretty specific strategy to beat them. If you don't have pretty heavy removal or graves, then most decks won't succeed as berry decks have excellent removal of almost every zombie, even whole boards of gargantuans, early in the game (don't want to go through the process of getting the screenshot here right now, but I have a great one of a massive army getting trounced with just a few sun while most of their guys remained... what's the point of the Cuke when you can do that?). They really do just cover too many angles far too well compared to most themed decks.
But, as I said, the biggest annoyance for me is really how it limits decks and is just too common (admittedly, at least in my case). Most well-built decks will be pretty successful against most types of decks. Partially because most cards were made with built-in weaknesses, but berries seem to have been built with the opposite in mind. While a couple of them have weaknesses, there are few good options to take care of the Strawberrian or the Sergeant without very specific cards.