Earlier quoted context omitted.
Using FTP as shorthand is better than "Object Store", which sounds like the marketing BS this is designed to avoid.
FTP implies a specific protocol. "File Server" or something like that would be better. You're quite right that "Object" is worthless terminology in this case - "Object" is basically nerdspeak for "thing".
This is a common issue in computer science and software development. Whenever new concepts are discovered or developed, they often need new names. You need to pick something that will distinguish this new concept from existing technologies. For laughs (kind of), look at configuration management software (Chef, Puppet, Cfengine, Ansible). They all quickly discovered that there were a whole bunch of new concepts that needed names, and while in some cases this hints that maybe these tools a bit over-engineered, it's hard to deny they've been popular and useful. Regardless, they all encountered these new concepts around the same time and they all made up their own names for them. So in chef you have cookbooks, where ansible has roles. Chef has roles where ansible has playbooks. Ansible has modules where puppet has providers and resource types. Ansible has tasks which are basically components of what chef would call a recipe and puppet would call a manifest.
All in all, I think "object storage" is a pretty fair term for the concept of a data store that neither heirarchical or sequential.