The choice of sampling rate has to do with the tech Sony had at their disposal. The first digital recorders were modified Sony U-Matic 3/4" video tape machines. NTSC resolution, combined with the ability to put only three bits per line (showed visually as black and white blocks), gets us to 44,100: 490 lines (525-VBI) x 3 bits x 30 frames.
To go a little further, the reason CDs are the size they are, is because that is as big as they could go, and still get a player to fit in a normal automobile dash opening. Originally, CDs did not go past 63 minutes, quickly went to 67, then 74. As the tech is maturing, we can now go to 80.
Hi-Rez is a moving target. We call it Hi-Rez because we have something to compare it to. Not really any different than comparing 33 1/3 LPs to Bernoulli Cylinders. We now have better (more) storage: DVD, Blu-Ray, and hard/flash drives. CD as a storage medium is the new floppy disc. The audio formats will eventually catch up, taking advantage of the new storage space at their disposal. Depending, of course, on the mood of the lawyers.