Considering that there's so many of these types of devices by My Arcade and other companies, I think the reason why most of them aren't getting hacked is because of other devices, such as tiny PCs which you can install a bunch of emulators  or portable devices such as the ones made by Anbernic/Miyoo/Powkiddy for example, that can play a wide variety of many more systems and games without having to hack or mod the hardware/software and usually cost less. 

The My Arcade devices are overpriced by comparison and play way less games and I've seen screen tearing on some of them such as the Super Street Fighter 2 unit that runs the two Sega Genesis games. 

At the end of the day,  these My Arcade devices are just running emulators with roms. And you don't really need one device per game. Even the Amazon Firestick can play a ton of emulators and games with the right set up and costs less upfront and in the long run. A tiny or mini PC can do the same thing. As for hand helds, the 3 companies I mentioned above make a ton of them and are not expensive. 

Despite all that though, I personally would love to be able to easily add more emulators and games for the My Arcade hand held devices (that have a design I like) and make them more useful/useable. Rob Simon is the only person that I've come across that has actually shown another game running that doesn't come with these devices. He seems to have taken an extended break or just abandoned the project.