There's a few responses here. I mean, i could launch.
But my actual response inevitably is: Because it's a game.
Every edition has changes. Some make no sense in comparison to previous editions. Some things in previous editions won't make sense compared to new ones. I mean, this goes like 500% for a sci-fi game. If you went by the stats, half the runners in the world were dwarves for a few years, then suddenly they're all orks, and now they're almost all humans. I mean, previous editions told us that in dates still in the future we wouldn't have developed wireless internet access yet. In retrospect that's either quaint or stupid, depending on how generous you're feeling.
But if you really want fluff ansewrs, here we go.
Think of it this way: a few years ago I kept all my data on hard drives, but chunky ones to (that in retrospect held actually very little). Nowadays I keep most my non-secretive data in emails. I literally just email myself schedules, work files, important dates, etc. I don't even OWN physical storage outside of one or two USBs I use to transfer stuff to one of my work computers, which has a janky broken internet connection. I am not alone in this! Theoretically this makes me more open to be hacked. I don't actually care. Most people don't. I don't keep a physical contact book. NOBODY I KNOW keeps a physical booklet with all the contact info for people. Technically, could my cell phone or my Google account be hacked, giving access to all the various emails or phone numbers I don't care to keep track of? Yes! This is a huge security downgrade from literally carrying a book!
It would not in any way, shape, or form surprise me if mandatory net access actually increased in how common it is. In a setting where the Matrix is intended to be ubiquitous, it would not surprise me in the slightest of stuff was created explicitly to only work fully when connected to it. For runners, this is the opposite of progress - but this isn't designed for runners. For the people these products are ACTUALLY manufactured for, everyone from corpsec to civilian gun nuts, this isn't noticeable. More and more people every day are keeping their credit card and personal info on their cell phones. Does this seem safer then carrying it in your wallet? I'm sure lots of people would loudly proclaim: "Good lord, no!" But it sure is more convenient! So the new smartlinks are designed explicitly to work over the Matrix, For Runners this is a potential security hole. For everyone else, this represents a smartlink that can be surgically implanted into your eye without needing to scoop out the things with a melon baller and replace them with cameras or give you horrifying data ports in your hands. For runners, having to connect your reaction boosters and wired reflexes to the matrix is a way to access your implements from someone you don't know. For everyone else, it's way to ensure your gear is always working at tip top capacity and that potential issues can be fixed through the Matrix without ever requiring you to see the doctor. And, most importantly, for corps, it means everyone who buys their product is now ALSO a tester and data collector of their product, so hey, they win out all around.
Convenience and profits always win in Shadowrun. Always. Every single time they win out.
The other thing to recall is that you kinda have to push SR4 to the side. SR4 was where the game started to run away from the "cyberpunk" aspect and embrace the "transhuman" aspect, except those two things are pretty much at odds with each other. Cyberpunk is almost by definition a dystopia. It's not a genre where technology owns and always makes everyone's life easier and you never make any sacrifices for it.
And hey, if you want a third excuse/reason, here we go: because cyberpunk is meant to capture the fears of the time and broadcast them onto the future. In the wake of information theft fears and personal data being sold willy nilly, "your information and personal details are broadcast at all hours" seems like just the thing to add to a dystopia.
