When reading reviews of cameras there are often complaints about features that could be easily resolved with external software, such as zebra patterning, intervalometers, HDR modes, custom menus, etc. However all camera manufacturers (if we discount phone makers) seem to use closed-source software with no official options for after-market modifications. Magic lantern has made some progress in fine-tuning Canon cameras, but their efforts are impeded by Canon's closed policy requiring extra effort for every new model on the market.
So why haven't we seen camera manufacturers embracing external development efforts? Is it that they extensively use sandbagging on low-end cameras to upsell their professional models? Is it that it would be too expensive to modify their firmware to support add-ons? Or perhaps most camera users don't really care for those extra features, so it would be a waste of time to open up your systems?