What's still lacking are digital stores which sell video files. DRM-free. Who needs circles if you can have a file and use it any way you want? But DRM poison prevents the future. So I wouldn't say it's arriving too fast. It's arriving way too slow.
If it's something I like, I prefer to have a backup of it and watch it where I want and how I want. I always do that with music, games and e-books. If it's one time use, then not making backups is more acceptable. You can ask same question about physical books. Why buy it and not just get it in the library? Similar answer will apply.
Secondly, unless that streaming is using some ubiquitous cross platform technology (like Web browser without DRM garbage), it won't be available on many platforms and will be tied to provided application. DRM-free file makes it platform independent.
Thirdly, I find it weird that streaming should be equated to inability to get a DRM-free file. Streaming is simply convenience (no need to download). But it shouldn't preclude ability to download itself. They are not contradictory, except in the mind of DRM pushers. For instance GOG's failed video service provides ability to stream video, and download it as well. Equating streaming to renting is incorrect.