Brookes, who taught Alan Titchmarsh and has designed 1,200 gardens worldwide in the last 50 years, and wrote the seminal book Room Outside (1969) said: "There are all sorts of novelty gardens and only so many permutations. They are going more and more bizarre. Some of them in order to catch the camera can look better taken from looking down which you only ever do in the garden unless it is from your bedroom window. I don't think that is very helpful to the public."
Brookes, who first attended Chelsea in the 1950s, said: "The public go for the experience and the day out but they want to take something home too.
"Anything with stainless steel looks alright in a city roof garden for a stockbroker but put it in any country garden and it looks very alien.
"And anything with water slithering down is difficult to use on a domestic level.
"But this is the way we allow them to be. It is not forced upon us. These showpieces are probably often not helpful to the public.
"TV has done it. Vast money from sponsors huge amounts the public can't afford. That's when things started going wrong. It got too big. Hampton Court maintains the feeling of the summer shows you get all over the country. It has not got that commercial thing that Chelsea has.
"TV producers don't allow analysis of the gardens and the public can take that. They should go in depth more."
Brookes was sponsored by the Financial Times, Inchbald School of Design and the General Trading Company, winning four gold medals for Chelsea gardens in the 1970s.
Garden writer Peter Seabrook, who is coordinating the four indoor Generation Gardens at Chelsea, said: "For the past five years designers have not designed for the punter. They have designed for the camera and for themselves.
"Often when you stand in the Main Avenue at Chelsea you can only look at the garden from one viewpoint. It's £40 to come in and you queue six deep and often can't see half the garden. That's why we always build on a square."
RHS head of shows development Bob Sweet said: "The designers know the gardens are going to get exposure through the BBC and they are going to do that through overhead cameras. That gives them more scope to do things. Some of Tom Stuart-Smith's Daily Telegraph garden (in 2008) was a little bit far away for visitors to see but was fantastic for the cameras. We have panel meetings to look at plans and test each application on how visitors will see them at shows. Examples are gardens which have obstacles. There are worries about how they are going to be seen.
"The 2007 best in show Mars garden by Sarah Eberle we worried how much you can see. There was a lot of detail inside but she pulled it off in the end."