I understand what you are saying. As I mentioned each persons needs\\desires are going to be different.
I use an HTPC with 4 drives in it for recording but want a large "disk storage" area for movies that is why I am going to go with the server. My main reason for adding 2 disks at a time is cost. I can't afford to build a box with 16 drives at once and with the costs dropping for drives I'll start with a couple 500GB drives then add progressively larger ones as the price drops.
My main interest in a box like Drobo\\TerraServ etc. is for my office and my kids so that they can store the shows they want since their HTPC's are microATX boxes. At this point I just don't see the advantages of this box especially after looking at some of its early issues and limitations. (network connection, 2TB limit, fan noise, USB only connection, changing RAID configurations, etc).
I will continue to read up on the system though, the do seem to have a good forum and do seem to get right back to the users that have posted issues and questions. That is a big plus provided they keep it up.
Good luck and keep us posted if that is the way to go.