The D'Addario 032 and 132 Chromes are available because (standard-tuned) 5- and 6-string basses were introduced in the meantime.
[Warning, guess-fest ahead:]
I have no explanation for the high C specific gauge, other than the possibile intent to offer a gauge that could work passably alongside both the 040 (against which a 030 would be about equally tensioned, but a 035 would be noticeably tighter) and the 045 (compared to which a 030 may feel too loose) G strings.
Regarding the low B, the difference between a 130 and a 132 is too small to matter, both slot-width and tension-wise, so I don't make too much of it; the non-round figure may be the result of the choice of specific calibers of core, underwindings and flat ribbon that they already use, but it's just an unsubstantiated guess of mine.
Now, why not go fatter than that?
The fact that no mass-produced flatwound low B larger than the Thomastik-Infeld Jazz Flat 136 exists is revealing. It is very possible that, given the inherent stiffness of flats due to the reduced flexibility of the flat ribbon, there are diminishing returns in terms of tone, and inharmonicity up the neck, vs. tension. This, combined with the lower demand of flats in general, 5/6-string sets (or low-B singles) in particular, and very large gauges at the end of the day (except from the low-tuning metal playing camp, who do not tend to choose flats anyway), apparently makes manufacturers decline to develop larger yet functional gauges.
T-I gets away with their 136 because their flats have a silk inlay that contributes little mass therefore tension, and because of other construction details: a thinner, round core, and maybe some trickery applied to the ribbon as well - a flat octagonal section, for less lateral contact? a narrower ribbon, like La Bella LTFs? I wouldn't know, never held a JF low B in my hands.
Likewise, Garry Goodman's Octave4Plus, the sole source of flatwounds of 140 gauge and larger that I'm aware of,
(
vd. Sub Contra Flatwounds - per the page, they also make flats in 150, 160, 170, 175, 180 and 188 gauge, plus a C#0 string of undisclosed diameter)
has devoted significant R&D to make building decently-working flatwounds with such gauges feasible.
Finally, why not make 115, 120 and 125 singles?
After all, the 055, 090 and 110 aren't currently included in sets - and haven't for who knows how long, as we've seen - and are therefore only produced in order to be offered as singles.
Well, I do concur it would be nice to have them.
(As it would to have the short- and medium-scale 080 and 100, at least, available as singles.)
I suppose they don't deem it as worth it to cover that gap as they do those other three gauges: perhaps they get little or no demand for a fatter low E than 110, ditto for a lighter low B than the sole gauge they make.
Once again, merely a W-A-G ( = "guess", not "girlfriend") of mine.
