When it comes to games (and movies, music, & books), I want to own what I buy. Under U.S. federal law, physical copies are treated as "sold, not licensed" and are covered under the First Sale Doctrine, meaning I can sell, lend, trade, or gift those copies at my own discretion. Digital copies are treated as the exact opposite, being considered "licensed, not sold." If you download a digital copy from the XBL Marketplace, Nintendo Store, Steam, etc., that copy belongs to the publisher, not you, and they can dictate if, when, and how you are able to sell, lend, trade, or gift a copy. If they do so, it's only as a courtesy, as they have no legal obligation to do so. And they can rescind your license at any time for any reason or no reason at all. That's not the only issue I have with digital downloads, but I'll leave it at that since the topic is about streaming video games.
To me, streaming is even worse than downloads. At least with a downloaded copy, it will remain on my storage medium of choice as long as said medium exists (however long that is; hard drives don't last nearly as long as a well-maintained disc or cartridge). But I refuse to invest in streaming games for the same reason I refuse to invest in always-online games. I just don't like the idea of a game that is completely dependent on having an online connection. It requires more than just a system, the electricity to power it, and the copy of the game. It also necessitates that your connection, the game's servers, and (if applicable) the online service you're using to all be up and running, and if any one of those things go down for any reason, the game is absolutely useless to you.
Streaming spreads the problems with always-online games to gaming as a whole because it makes even single-player games dependent on a constant internet connection. If I'm unable to connect to the streaming service for any reason, that means no playing anything until the connection can be re-established, and the quality of my gameplay experience is dependent on the quality of the internet connection. If a game is removed from the service for any reason, such as being rotated out Netflix-style or simply being de-listed because there was some sort of rights issue or the publisher went under or just wanted to stop making games (like when Irem stopped making games and forced Nintendo, MS, & Sony to temporarily de-list every Irem title from their digital stores), then you don't get to play that game until it gets re-listed, which may never happen depending on the circumstances. I don't have these problems with my offline games. My NES games are still perfectly playable after 30 years, as are every other physical game I have. Same with movies. I have Ghostbusters 1 & 2 on Blu-ray. Good luck watching them on Netflix, since they were removed earlier this month.
if streaming continues to be an option, and only an option, I won't mind its existence, but the moment the industry abandons physical games is the moment I abandon them. And it irritates me immensely when people hope and actually push for a digital-only future. There are people out there that, whether they realize it or not, don't want me to be able to buy physical copies of anything anymore. They don't want me to have the option. That's what I hate. The claimed "convenience" of digital does not to me outweigh what I feel are significant drawbacks. In fact, I feel the supposed convenience of digital is vastly overstated. I have muscular dystrophy, yet I'm not beyond taking the less than 30 seconds needed to swap discs (I timed myself). So, you might save maybe 20 seconds every time you switch from playing one game to another if you have them digitally. Is that really such a massive time saver? And then there's the "I don't have to get up to switch between games" people, which for able-bodied people is just laziness and is an argument that can be summarily disposed of.
Also, I've seen a couple of people bring up the environmental impact of physical games, which is also vastly overstated. As of Dec. 31, 2018, there were 876 million PS4 games shipped globally. Now, presumably not all of those are physical copies, but let's assume that about 80% of them are, meaning about 700 million discs. One PS4 disc is about 13.57 cubic centimeters, so if you melted all those discs down and made a cube out of them, it would be only about 9.5 billion cubic centimeters, which sounds like a lot until you realize that that's a cube only a little over 21 meters per edge. That could fit into my small-ish back yard, and would only be a tiny section of the typical landfill. And the game cases (original dimensions, meaning not melted down, since they are storage boxes) occupy only about 23.67 times the volume, meaning a roughly cubic shaped stack of 700 million PS4 game cases would be about 61 meters per edge. So, even if every PS4 owner threw out all of their physical copies, case and all, the amount of garbage would be far, far from ruinous (in the U.S. alone, all the garbage tossed in one year amounts to a cube 805 meters tall), and I'd submit that only a tiny percentage of those games actually will be discarded. Oh, and game discs and cases can be recycled.
If you want to use minuscule time savings, or laziness, or keeping your garbage to the most absolute minimum humanly possible as reasons to go all-digital, then by all means go all-digital, but don't insist that the rest of us do so as well. A Nielsen survey from last summer showed two-thirds of console gamers prefer physical copies. The demand for physical is real, and if that demand is ignored by the industry because of some push for a mandatory digital/streaming regime, then they don't deserve my money.