I can't tell you why it's designed this way, since I don't have the ear of the product developers. However, I can say that your core concern about up-time is being addressed.
I have a 55" LED with a 'Smart Hub' system. Tonight, I went to use Amazon on-demand video but couldn't. The TV provided this extremely helpful error (sarcasm) "ERROR_MODEL_BIND - Network not connected - check network settings". Some quick Googleing resulted in a few results suggesting I 'factory reset' my TV which didn't help and only served to frustrate me further than I had wiped out all the apps I had installed. I knew it wasn't really network related as my home network is fine.
I chatted with a Samsung rep who informed me that the SmartHub servers were down. Ok.. but I don't need to install any apps or use SmartHub/Samsung provided content - I want to watch Amazon on-demand. I came to the conclusion and the rep admitted this that all applications (even though they are downloaded to the TV) have some dependency on Samsung's bigbrother/mothership servers being online and operational in order to run.
Please explain to us why an app that is 1) downloaded to the TV 2) streaming content from non-Samsung servers is required to check-in with the mothership before it can deliver content? I can get into 'smarthub' and the application is downloaded to my TV so I know there is not a technical limitation here.
Why would Samsung put a service together than has such a strong dependency on its own servers that from what I can see have a poor track record of uptime (googling shows several lengthy outages over the past 6 months)?