One thing that does strike me, is just how un artistic many suppossed garden designers are. In a previous career I used to carry out alot of work for different landscape architects and garden designers, some very well known and some not so. One thing that they all have in common is a complete lack of flare and originality. Without fail you could walk from one finished garden to another and sadly know who designed it. They all just follow the same boring trend, and this follows through into education. I've frequently seen students posting questions on forums about trends etc, and to me this is a major flaw within the landscape industry. Teachers should be teaching the students to set trends, not just follow what is already out there.
One designer who does think outside the box and who I've always admired, not least because he isn't afraid of using concrete as a design medium, is Diarmuid Gavin. You can still tell which gardens are his, but at least he tries and isn't afraid to be different.