100% agree, would love to see an ecosystem whereby one "Smart" controller could be used across your entire fleet, but currently that is only a reality in the open-source world of UAS. DJI is close to it with their current SC being compatible amongst their consumer and prosumer offerings, but a divide still remains in their commercial/enterprise offerings. It has also taken some time and future aircraft generations for their SC to be compatible across many aircraft series, it wasn't that way from the start.
Back to the open-source world...today this ecosystem remains quite a bit behind the curve of what proprietary and "closed" system manufacturers provide in their UAS offerings, feature sets, payloads and capabilities. A quick glimpse of this is shown by the Blue UAS platforms. Some of these systems rely on open-source flight control software and some open-source handheld GCS. We are seeing great advances in the "open" world of sUAS, but the offerings aren't in line with the systems we see from the likes of DJI, Autel, Parrot, Skydio, etc. In addition, the hardware in the open ecosystem in itself prices higher than fully developed proprietary solutions, and from there you've still got configuring, coding, and developing to achieve the solution you need with the hardware components in play. Systems that are fully baked, RTF (ready to fly), and commercially available off the shelf that are in the "open world" currently price 2X that of the proprietary offerings, and that is with less feature set.
Following the "leaks" on the imminent DJI Mavic 3 and new DJI Smart Controller, it will be interesting to see how compatible DJI's second gen Smart Controller will be across their product lines.