No, not necessarily. But some diffusion is usually a good thing. Using a 60mm lens, as I did here, puts me only about 5 cm (2 inches) from the flower, so it's easy to catch a lot of reflections from the flash, which again means burned out highlights. The twin flash set allows me to control that pretty well.
lol. i was laughing when i wrote your comment cuz i was thinking that except for like the roses and hibiscus - none of my pics have the name of the flower in it. I usually wait for someone to say "Oh what a nice _______" Thats how I find out what they are. O and as far as the Gerbera, you just educated me.