It’s more than that.
Most of the planes we work on have glass cockpits and require sim popouts. That means suddenly, the holes we have to make in background images to let the popouts show through have to be a very particular sizes and don’t scale at all. If it were just flat graphics without said holes, that would be another matter altogether. It’s not just a matter of cropping and scaling. It’s a matter of having to do some major edits to the background graphics, which quite honestly, is beyond the both the skill level and caring of most end users. That in turn will cause complaints since the panels “don’t work” on a particular user’s setup, create support requests on Discord, unhappy users, and a bunch of work for nothing.
The panel building tool in AM is tedious to use. Building full panel layouts for planes is a fairly lengthy process. And most folks wouldn’t know how to edit / manage those themselves to make the changes needed. Which again generates support requests.
Again, we do this for free. We provide users with high grade free instruments that are superior in visual quality to the majority of stuff currently in Air Manager, completely tailored to specific MSFS planes. We strive to ensure everything works and looks as close to the real thing as possible We put literally hundreds of hours into development of said instruments and we take end users 95% of the way to their final cockpit layout. Even if we provide full panels, we’re still only taking the majority of users 95% of the way as they’ll still have to do a bunch of work and rearranging to get their layout working on their own monitors.
On a side note, I’ve never shied away from sharing my background images for my panels over on the Simstrumentation Discord. I even posted both the PNG and source PSD Photoshop files for my C414 panels in the Simstrumentation thread sp that people could edit them to their liking (assuming they use PS). I’m happy to provide said backgrounds if people want them. But personally, that’s as far we’re willing to go.
Honestly, most of my backgrounds are simple flat graphics. I have a carbon fibre texture I found on Google and use that for the background for most of my planes. I just cut the holes in it for my popouts to show through and call it a day. I only have a couple of planes where I’ve bothered doing more background panel work.