It makes more sense sense when you think of Glacier as a tier of S3, like Infrequent Access/etc which it is now. There used to be a Glacier standalone service but you had to upload a blob and track the UID to file name mapping yourself. That skipped S3 but was far more complex.

Workspace make more sense for large amounts of data where you can take advantage of the "unlimited".

Backblaze B3 might be what you are looking for as an in between option.