| "these ones" is redundant |
|
Well, yes, but then "this one" is equally redundant, isn't it?
Or is it that "this" and "that" alone are used to refer to abstract ideas and situations, whereas "these" and "those" are not used that way?
In that case, the function of "this" and "that" as abstractions and their function as pointers to particular instances of physical things can only be kept separate if we have "this" AND "this one", "that" AND "that one". On the other hand, the same cannot be said of "these" and "those"; they are always used as particular intances of things, so there's no need for separation into a "these" form and a "these ones" form -- same for "those" and "those ones".
To be consistent, there should be a "this" and a "that" for the more abstract or general use and "this one", "that one", "these ones", "those ones" for the more specific references, but the evolution of language is not always as neat as it could be!