What is the problem if sun is behind me?
It is not about boring or not boring. It is about pleasant.
1. Harsh light
It is well known that diffuse light is better for portrait photography for example. Sunlight is the harshest light on this planet. Ugly shadows, shiny skin, flat light.
2. Blind your subject
Sun behind the photographer means one thing. Direct sunlight on people's faces. They will close the eyes, and wrinkle the face to avoid being blind.
3. Flat light
The only worst light you can make on the planet is a direct flash from the camera. The same applies to a building. It will look flat. Remember that light is as important as your subject.
4. No mood
A flat light constructs no mood, there is no romance, mystery, joy, sadness... Just a photo.
Find out for yourself
I was tempted fo find examples on google. But this is something you should find out yourself.
Go and take some photos to a person on a park, a plaza, and rotate arround; take photos with light behind you, on a side, sun in front of you, etc, and compare.
What does that signify?
If you are on a trip visiting a city in another country and you have limited time, you could potentially only take one photo regardless the sun position. "Se la vi"
But if you can plan your photo, having the sun behind you means that you are not paying attention to, not details, to light itself.
Means that you need to practice a lot more photography and not just be a spectator. You need to control your settings, your environment. Bring a cloth to diffuse the light, move around, use a fill light, wake up early, change location...
One exception is when the shadows including yours are one main subject, and they form a part of the story in the picture.