I generally prefer Digital over Physical as well, but in regards to the Vita, I don't. Right now the largest card you can get is 32GB and if all my games were digital as oppose to physical I would probably be maxed out if not close to it right now. Furthermore, that 32GB is not cheap and the digital copies either have little to no discount in comparison to the physical. Financially (regardless if I can afford it or not), it just does not make sense.
As for the point of wanting your games readily accessible from the OS... Well, you will only be able to have so many games accessible at a time with the max 32GB. Granted you don't have to download/install every game, but then that game is not considered accessible. Also you could load different game on to different memory card, but that makes it about the same as carrying physical copy (actually worse since the Vita reboots every time you change the card).
Sony has already stated (or atleast I thought I read it somewhere) that they will be coming out with larger capacity card, which will help (at a cost) the first part. In then end, each of us will do what's best for us and at least Sony learned from the PSP Go to at least have an option for both (even though pricing could be better).