Quite a few reasons but it's just not as versatile and useful for us, and camera technology has changed a lot in 2 years! Back when we bought it we primarly used 5DIIIs anyway so it was great but now we only touch them for photography. DJI still don't do a gimbal for our A7SIIs and even if they did we'll probably be changing cameras in a year or two anyway.
The quality they're getting from the DJI cameras is also fantastic - certainly good enough for everything we produce - and way more versatile due to weights. The main reason we were holding onto the S1000 was for aerial photography but even the Inspire 2 can capture 20MP images now.
Going back to one flashing LED for all error and technical readouts compared to via DJI Go feels a bit like the stone age as well.
We also bought the DJI S1000 with half an eye on entering new markets and doing higher end broadcast and film production. Those requirements have increased and we'd need to drop 50k+ on kit to compete efficiently, and we'd rather concentrate on utilising UAVs to compliment our existing ground offerings rather than being entirely standalone/specialist.
We've been using the Phantom 4s a shed load this year and they've been fantastic for extended flight times and a lower MTOM. We need to apply for blanket congested area flying as well and one restriction we'll set ourselves is only flying <7kg.
We'll likely get the Inspire 2 before March anyway but anything we get from the S1000 and its bits will just make it feel less wasted, otherwise it'll just sit there getting dusty.