For the vast majority of folks, all they need "right away" might be cable assemblies (cable+connector) or batteries. Radio Shack can't make a profitable business from those items alone. For the serious hobbyist or DIY person--and there are some out there--it's easier, smarter, and cheaper to get your BOM filled online if you can't get to a Fry's or equivalent nearby. Radio Shack is stuck in the gap in the middle, not a good place. And the "iconic" name sure doesn't help, either.
I guess it's like Kodak--when change came, there was little they could do about it, despite what all the pundits said: "they didn;t adapt, even though they invented the digitla camera." Fact is that their entire business model was based on selling consumables like film and chemicals and processing, not one-time items like cameras (those were almost an incidental business for them). And Kodak had lots of IP and patents, unlike Radio Shack, so RS is in a far more precarious place.
As a kid, Radio Shack was my favorite store and I often went there to buy parts and to learn about new components. Now I'll admit that I buy big ticket items online (better selection, ability to compare and research alternatives, avoid a trip to the mall). Radio Shack is the place I go for parts once a year when something breaks. It seems that they are the "convenience store" of electronics. If you want tools, there are home improvement stores, if you want cell phones there are cell phone stores, but if you have a shopping list with a variety of items then Radio Shack gets a visit.
You-Do-It has been around for years and has adapted well. They're more heavily into selling things like computer cables and other IT infrastructure, bu they still carry lots of components, meters, ham radios, and the like. They even had one oscilloscopes when I was last there. It's a 30-MHz, two-channel analog model from Elenco.
Well, for what they charge for cable assemblies, RS must be getting a pretty big profit margin... when they're able to sell one. RS is a good place for cordless phone batteries, the occasional connector, the occasional LED, and the occasional switch. However, the part selection is so limited compared to (say) Digi-Key, that it's rarely worth bothering.
I used to buy surplus parts from a basement store called Verada 214 in Lowell, Mass. The cabinets for the Utah speakers I bought at You Do It came from there. I also bought a National Semi MM5316 digital clock chip and built a clock. It still works although the LEDs don't put out much light anymore. I still have the MM5316 data sheet.
One of the highlights of getting my driver's license "back in the day" was that I was able to drive to Lafayette HQ/main store, instead of being limited to their smaller store near my house (a short bus ride away). Going to Lafayette by car the first time, in those pre-GPS days, was an adventure in itself. On the way back I stopped at nearby Eico (a vendor of kits, like Heathkit but smaller) with an AM/FM tuner kit I built, didn't work. They were nice enough to send a technician out to look at it, turned out it was a defective front-panel rotary switch (they gave me a new one). That kind of customer service is long gone!
RS's selection is too limited; heck, even Fry's is limited, but they do have stuff that's handy in a pinch, like a good selection of resistors, DSub connectors and adapters, and such.
But my normal retail shopping is Excess Solutions, and maybe All Electronics (more electronics, but fewer connectors & such); I haven't been to Halted in a long while -- and those three are about all that's left for Silicon Valley surplus. There used to be a lot before the Dot-bomb bubble destroyed most of them due to rising rents.
For industrial stuff like servo motors, eBay is the place.