The Rodenstock 23, 28, 32, 40, 50, 60 and 70 are all *excellent* TS wide angles that you can use with a Phase One; more options than you'll find on any small-format system. You can explore their
relative image circle sizes here.
What you mean is "Why no TS Wide Angle for the Phase One XF (yet)"?
I can't speak officially for Phase One, but here are some points of reference in which I am highly confident:
- Phase One only wants to release lenses that are A+ quality. Since 2012 they have not released a single lens which was not excellent or better.
- The benchmark (point of comparison) for a TS lens on an XF will be very very high; as you note the 35LS BR is an extraordinary lens, and any TS that is not at
least that sharp will disappoint many users
- Lens design is a compromise between image quality, size, weight, image circle size, and cost. The 35LS BR already shows what happens when you maximize image quality without much constraint on the other factors (it's large, heavy, and expensive). If you now want both that image quality AND a larger image circle the other factors (size, weight, and cost) will have to increase.
In other words, they may not think there is a market for a lens which is larger, heavier, and more expensive than the 35LS BR. Especially when users who really want that functionality can already get an Arca, Cambo, Alpa or similar tech camera and use a bevvy of the world's best glass with tilt, swing, rise, fall, and shift built into the body (which is preferable to having the movement on the lens).
But personally I think they should go for broke. There are numerous users and use-cases for a suplerlative TS wide angle on the XF.