a screen probably seems pretty useless a lot of the time, get a screenless camera and try and troubleshoot it though, it can be very frustrating trying to work out what's going on at times with cameras that have no display, some have wifi which kind of helps but can also have their frustrations, wifi is another can of worms, ask anyone that sells a product with wifi how many support calls they get, then there's the models with nothing but status lights, trying to remember what flash means what at some time down the track can be like trying to crack the davinci code on some products
no screen is the cheapest way and the most hassle, on most models adding a screen adds about 5% to the cost and saves a heap of grief, adding wifi just to go without a screen is the most costly and not always that easy, in short a screen is a cheap way to make the product very simple to operate at minimal cost