I just have an undergrad degree in linguistics.
I am looking at this question from the perspective of x-bar theory, and defining "tense" as as a feature of the syntactic catagory that populates the populates the "T" node at deep structure (or a feature of the I catagory). [0].
As I alluded to in my comment, I have never seen a convincing arguement in either direction for wheather "will" is a T or a V; and this was an active discussion in my syntax class about 3 years ago where the proffesor (a syntaxtician) had also said that she never saw a compelling arguement either way. If you know of one, please sharer.
Edit: I think you edited your post after I responded. I would argue that all languages have the same featureset (including tense) at d structure, but that is going far afield.
Edit2: there is also a notion of tense at the sementic level. And English seems to offer a gramaticalized way of providing the sementic future tense, regardless of how you look at the corresponding syntax/morphology.
If we accept that "will" is a syntactic "T" and carries a sementic meaning of "future" then how is it unreasonable to call it a future tense? Sure, there are debatable parts to the above assumptions, but it is a stretch to say that no analysis has future tense. Heck, there is a universal grammar analysis that would say English (and Chinese) has all the tenses, and the only question is which ones surface as distinct pronounciations.
[0] This leads to a notationally weird case where "to" is a tense with a -tense feature.