I liked the texture of the flowers and the yellow. Also I was quick to spot that if I crouched down on the rockery, I could fill the background with the green bush. So I knew I could blur the background as much as possible, to isolate the yellow flowers. I had this printed out at work today (along with a few others), which are my first prints since buying a DSLR. I think this makes them look even better than seeing them on the screen.
OK, Just for fun I've 're-worked' your image slightly by cropping. I've done nothing to exposure or colours etc.
So, the answer to 'Why?' is the texture of the flowers. So, the answer then should emphasize that texture. In the photo you are showing, however, there is a lot of 'background' showing... so the viewer may be confused about you are trying to show.... flowers, texture, background, etc. It is that 'confusion' in the viewer's mind that can weaken an image. All I did was to crop out a lot of background that surrounds the flowers. The flowers now dominate the photo, and it is more clear that the photo is about the flowers, not the texture of the background.
I could have moved the bottom crop up closer to the flowers. On the one hand this would emphasizes the flowers more, but I think in this case the flowers without stems wouldn't look right. I could have also cropped it to a perfect square. In this case it is so close to be square that if this was mine I would take the time to do this. A 'nearly' square crop often tends to look a bit funny.
I am not familiar with your specific type of camera so I don't know if it is a full frame sensor or what, or if the focal length data reported is actual or 35mm film equivalent. However, I will say that it appears you are using either a 'normal' focal length (i.e. nearly a 50mm lense with 35mm film equivalent -which sits between wide-angle and telephoto) or at best a short telephoto. Try the same shot with a longer telephoto. Long telephotos will crop out more of the stuff behind your subject (that messy bush on the right would have disappeared) plus they give you a much shorter DoF... so the pine needles behind the flowers would have gone much more blurry ... and wouldn't have been a distraction, as I (personally) believe they are now.
Finally - I've circled 3 elements that I think are visual distraction in your composition ... the 3 blades of grass. The one on the left because the brown tip sits in the same visual line as the flowers. It breaks the nice repetition. And the middle and right hand grass because along with the brown tip they cross the strong verticals with a diagonal line, and that upsets the repetition of the strong vertical lines of the stems.
Personally, I think I would have removed all the grass stems and left just the flowers.
However, making these kinds of compositional changes (specifically moving or removing grass) may lead to some serious soul searching. If you are shooting 'natural scenes' how much can you play with what you see before it is not 'natural' but composed? Can you remove something entirely and not leave it in the scene at all, or can you shift it to make pretty good scene excellent. Can you move things when shooting, but in editing mode? There are no right and wrong answers here - except those you set for yourself. Everyone will have a different opinion. And you should also accept that the 'rules' you set for yourself this week may change over time as you think these things through and talk to other photographers.
Hope you don't mind the long post.