I think the only thing you're missing is this:

1. Lutron makes a dimmer (or a module) to control virtually any type of lighting load that exists (Incandescent, magnetic low-voltage, electronic low-voltage, neon/cold cathode, fluorescent, LED etc) and Insteon doesn't.

2. Lutron dimmers and keypads are available in just about every color of the rainbow. Insteon's aren't.

3. Lutron, the inventor of the solid-state dimmer, has been around a long, long time; it is a huge, world-wide company; it makes lighting controls all the way from the lowly stand-alone, dumb dimmer to huge, commercial lighting control systems for high-rise buildings. Insteon does nothing of the sort.

In other words, Lutron isn't going to disappear overnight and it has any lighting product and style that you could ever need. And they work. 100% of the time.

I guess that's all you're missing.

(Have you looked into the third option? Using URC-branded wall dimmers and tabletop lamp dimmers made by Lutron specifically for the URC MX-980 and other models?)