Well yes. Of I have to wait for something to be shipped and it contains lots of excess songs I dislike, that really isn't really "readily available". That's just "available" and it's only available as long as EMI and Amazon have stock.
Honestly, this is why the iTunes music store exists and why Piracy existed - people didn't want to waste time with a CD.
As a former small town resident, I entirely relate to what you say on availability. CD clutter isn't always attractive, but it is good to have a backup of ripped music. I rarely play CDs, and rarely buy them, though my wife still mixes CD for her car. There are few albums where I really love more than 50% tracks. These are the reasons I am a pretty loyal iTunes customer.
That is a valid point, however, I don't call a store bought CD as a "backup". I mean for the most part you keep your CD's at the same place you keep your digital tracks - at home. And CD's are not permanent records either. Any backup is only as useful as the medium it is stored on. And it's not as if digital content can't be backed up either. If you want to get detailed about it, nothing is really considered "backed up" unless it is in 3 different forms (even I don't do this).
My overall point is that CD's shouldn't be the only way to enjoy something. IMO that is a silly excuse to justify the status quo and does not address the root concern - there is demand for the Beatles on iTunes (or other services). Yes, the CD's are out there, but not everyone wants to get CD's. And no, having the complete CD's is not the only way to enjoy things - the fact that there are compilation albums and the fact that iTunes has been doing so well selling music individually proves this. All the people who are suggesting buying CD's and implying that everybody already owns it are making really broad suggestions.
Imagine it like this. I and lots of other people want to go from California to Florida. The problem, no airlines exist that will take me there (not even the private ones) since Florida airports hate California (despite the fact that the airliner want to offer that route). Any other plane route in (say connecting flights) is like ordering CD's - time consuming and takes me to places that I might not want to travel. If I want to go to Florida, people are saying "Big deal - just take the bus cross country, or a cab (better since you can see the country!) or walk" or "big deal, just take an indirect route and pay a little more and have the benefit of more travel. Yes, they are valid ways to get to Florida, but they ignore the root problem and their are band-aids at best and they don't fit everybody's requirements. Some people want to hitchhike, take the bus or do connecting flights. Not everybody want to do that and it is frustrating that despite what the airlines want to do, somebody is holding up convenience for the customer.