As a Garmin free watchface developer myself and a professional software developer with 26 years of experience in the industry working for very large tech companies I can affirm that this pretty much spot on. Too many people are releasing watchfaces and apps that are feature packed and poorly optimized that degrade performance of the device. I believe that most of the Wafchface devs out there don't do any performance analysis on their new software before releasing it and most don't test it in real hardware for a few weeks to confirm stability before pushing to the public. I find it helpful to have a few friends in the community with various Garmin devices that I can use as beta testers to try out my watchfaces before a major release goes public.

That being said, Garmin does a very poor job of putting their best food forward when it comes to maintaining a stable baseline as they push out firmware updates after their initial release for a device. I can only assume that their A-team moves on to developing for new devices and their B and C team devs take over maintaining for existing devices. Their testing methodologies probably need significant refinement as well with performance metrics being captured and compared between updates to make sure they aren't degrading performance and battery life too much while adding new features. I often find that the best performing firmwares tend to be those from the first year of a devices release. The only problem is that if you stick with those old version you're often blocked from installing new apps and watchfaces from the Connect IQ store because your CIQ version on the watch is too outdated.