It’s an interesting proposition and I can definitely see the value in certain situations like this. Community feedback is a key part of how we prioritize what we work on, so creating your post is a good first step. The more people that voice an interest in specific features, the more likely they are to get prioritized.
I’ve gone ahead and split this discussion out of the Multiline Hero Attribute and Sorted List - #12 thread and into it’s own topic to give it a bit more visibility as well. (Feel free to rename the topic title if you don’t like my summary) 
Alternative Approach: Child Devices
In the meantime, a common workaround for other device types which either have multiple on/off states or multiple controllable levels is to use child devices.
Often times, the core control is all possible on the main ‘parent’ device using custom commands (like the setSlatLevel() command in the device you linked to.
Then the ‘parent’ device might also have child devices for convenience. For example, a ‘Slat’ child device that offers a standard setLevel() command under the Switch Level capability so that it can be used in other apps like SharpTools which implement things against the capability standards that SmartThings has defined. (This also opens up functionality with a bunch of built-in SmartThings apps as well)
–
For example, my custom Wink Relay device handler… the device has two relays built-into it meaning it can control two different loads. Using an on/off command on the parent device will cause both relays to turn on or off. The parent device also has custom relay1On() and relay2On() style commands for controlling each relay. It also has a child device for each relay… so you can directly use standard on/off commands on each individual relay making it easier to use in various SmartApps (including built-in ones like Smart Lighting and the Custom Automation builder).
Perhaps you could suggest this to one of the DTH developers to see if it’s something they would consider adding? Or if you’re up to it, you could perhaps contribute the modifications. 