I've thought about that, but then you lose the ability to use these devices with these drivers in "standard" apps like Button Controller or even with Rule Machine and a "Button Device" trigger--you pretty much need either a custom app or a custom-trigger Rule. So, it certainly works and makes things a bit less messy in the numbering world, but there are downsides to either approach. The other approach I considered was making each button a child device, but then you get lots of child devices for a single device, which some people also find messy (and you still have to handle the multi-taps, but "buttons 1-5" for each child button might be easier to do in your head, I suppose!).
For anyone interested, here is my first attempt at the driver I mentioned above:
...including all 25 button "pushed" events. 