Sounds like you need a new kitchen… . I actually replaced a fixture in my laundry room with a single-bulb fixture because it was a pain trying to find those double circular fluorescent tubes. If you have some basic tools and know how to turn off a breaker, it might make your life easier to replace the fixture with a 2-bulb. If not, that splitter @gemniii suggested seems like an interesting option.
To sort of answer your question, 60W equivalent (~800 lumens) is the most commonly used bulb so it makes sense to produce that (and cover the 40W range at the same time with dimming). 75W, 100W, and 150W bulbs are less common because they’re usually too bright or hot for most fixtures, and supply/demand would probably make them too expensive. Also, heat is bad for the “smart” piece of the bulb, so that probably contributes to the challenge of producing them.
Another thing to consider, some smart bulbs say they are 75W equivalent (1100 lumen) but actually put out more like 900 lumens, The “100W equivalent” (1600 lumen) smart bulbs I’ve seen only put out ~1200 lumens, and I’ve never seen a 150W equivalent (2600 lumen) smart bulb.