Often I get asked by perspective clients, if they should redo their driveway or patio etc. My response is always the same. If it's cracked then yes. If you cannot stand to look at it anymore, then yes. But if there is nothing wrong with it then why? Why fix something that is not broken or in need of repair.
There is also the aspect of cost. As it relates to hard surfaces, the biggest cost is not necessarily the material but the the labor of removing what is there and the labor of installing something new. If you can save yourself that cost then I would highly recommend it.
Regardless of what you do I would also recommend that you gather images of what you like, especially pics of garden that have the same hardscape that you do. This way you can see how others have made that same surface work. I would also gather images of hardscaped gardens using materials that you might replace it with. Then when you meet with a designer, he/she can tell you if what you already have is workable and if what the new desire is will work with your budget. Most designers can tell you if your budget will work or not. The key is that you have to be open to compromise, unless you have a lot of money to spend.