Most of the latest and greatest computers not including an optical drive are ultra thin laptops that are not particularly fast, with battery life and weight being the only advantages they have. Apple is also ditching them on all of their products, probably so they can make more money on their App store and iTunes. You can get external DVD drives that connect via USB if you do need one for one of those computers.
For desktop systems, it's easy enough to add a DVD drive if you want to, they only cost $20 or so, so removing them doesn't save you a ton of money. Price is only really a factor if you are talking about BluRay drives, and only consoles use BluRay discs for software distribution, on computers BluRay is only really useful for watching movies.
They're good to keep around, just in case you need to use the Windows install disc for recovery purposes, or need to load a driver from a CD when you don't have internet access for whatever reason.
Right now my most used optical format is BluRay, which I use because I don't have an internet connection nearly fast enough to stream full HD content at any reasonable speed. For people with slow internet or prohibitively low bandwidth caps, discs are definitely still useful, especially with games that have constantly ballooning space requirements. Some titles are exceeding 30GB, which may take ages to download, and eat through 25+% of your monthly bandwidth cap.