I'm not 100% sure if this has been suggested yet, but it wouldn't hurt to post it anyway.

One-in-four marking applicators were changed during the anniversary last year, no longer randomly selecting a marking for you and instead letting the player choose. However, this change did not apply to Mutie on Demand: Piebald and Mutie on Demand: B&W Patches.

MoD: Piebald has a 1/7 (~14.29%) chance of giving you the mutation you want, and MoD: B&W Patches has a 1/6 (~16.67%) chance of giving you the mutation you want. Both of these applicators are significantly more expensive than any of the event marking applicators, and real money is required for another to be added to the economy. (For example, Rose Pink Kisses is currently 25gb at its cheapest, while MoD: Pie is 200gb and MoD: B&W is 195gb.) It's significantly more expensive to try multiple times for the mutation you want, especially because there is nothing preventing you from getting the same mutation multiple times in a row.

My suggestion is simple: adjust these MoDs so that they have a dropdown selection similar to marking applicators. Removing the gambling aspect could increase the demand for these applicators as well.

EDIT:
"Won't this lower the price of the mutations in these MoDs?" The pie/patch market is already abysmal. Let's look at the prices of these mutations together. Please note that these prices can and will change in the time after this edit.

The majority of Croupe lions on the market are 3gb or less.
Half of the Dense lions on the market are 4gb or less.
There are 2 Frontal lions on the market. They are both 2gb.
The majority of Clouded lions on the market are 4gb or less.
The majority of Slender lions on the market are 2gb or less.
The majority of Harlequin lions are 4gb or less.
There are only 3 Bisected lions on the market. One is 12gb, one is 2gb, and the other does not have a price.
More than half of the Broken lions on the market are 3gb or less.
Half of the Heavy lions on the market are 5gb or less.
All of the Light lions on the market are 4gb or less.
More than half of the Mosaic lions on the market are 2gb or less. This statistic DOES account for the 100+ GB YoRHa Mosaic cubs. Ignoring YoRHa cubs, the majority are 2gb or less.
The majority of Mottled lions on the market are 2gb or less.
The majority of Symmetrical lions on the market are 2gb or less.

Despite being "rarer" due to the gambling aspect of their MoDs, you'll notice that most of these mutations have the same prices as their standalone-MoD counterparts.