Today we can put a cushion in anything. We can make any piece of furniture into a cushion or line it completely with them. We can even use them outside in order to create unusual settings that no one has ever seen before. You can get any form or color that you would ever want from it and even have many items custom-made. The line between cushion and art is also blurring due to the many possibilities which we have today.
You probably at least need a cushioned piece or two no matter how you have everything set up. Unless you have a really strange set of friends or clients who love having hard wood and stone to sit on it just makes sense. Many people do have just a single, rough piece but that is not usually because they want to. It is because they bought it and never replaced it.
For those who really want to take it to the extreme it is possible to do a fully cushioned room, outdoors. However it would take a huge amount of planning and work to do this. You would have to buy the best cushions and even pad the patio floor. This has been done here and there but is so prohibitively expensive that only those who have thousands upon thousands of dollars would want to do this. Unless you have a very small patio. You would also have to maintain it at a high level all the time.
Due to how easy it is to make you can find items like this all over the world. Even ones that are weather-resistant are becoming more common. Unfortunately you still need to maintain all of these on some level because no matter how tough they are these can wear down over time and grow mold. So be sure to clean all of these regularly so that this does not happen.
Being flame retardant is also another important thing to think about. While it happens rarely someone could have an open flame end up on your sitting arrangement and it would all go up in smoke. Lightning could also hit it and while that is of course very unlikely, it has happened to various people. Nature can be unpredictable so make sure you are prepared for any sort of eventuality when it arises. Fortunately this is extremely rare and only really happens around open flames.
Memory foam and other new materials are also being tested with these. Unfortunately they are not all equally resistant to Mother Nature so you should only use these if you are sure you can keep them away from rain, snow and the elements. If you can then it is fine but you do not always have time to respond to every single thing that might happen. Some new multifunctional pieces are ready to be used though, many have strong cushioning.
You should take note that in areas where there is a chance of theft these can be a liability. Since they are so easy to carry they can be stolen much more quickly than most Outdoor Furniture. Try to only use these in an area that is very safe.