I won't buy anything online, although I'd like to be able to. But currently, I won't invest in what could amount to hundreds or even thousands of dollars over time on file formats and bitrates that may sound like crap with great headphones, or may not be compatible with most devices. iTunes would be the best example of this.
For me, ripping CDs and having the power to convert that content to whatever format and bitrate I choose (and is best for me), is the only way to go. That's future proof because not only are CDs not going to disappear anytime soon, but no matter how encoding technologies develop, there will always be a way to rip and encode your own CDs to whatever supported formats exist.
I wouldn't say that online stores are in their infancy, but they have a LOT of growing up to do. IMO, they just aren't ready for primetime - too many things to iron out.
It makes more sense to me right now to join a record club like BMG Music and do my own thing.