An industry in general having a high turnover rate does not equate to one single project having a high turnover rate and moreover it does not mean that it bodes well for that single project. Perhaps reducing turnover rates in the industry would mean better quality in the products coming from that industry. Gaming is fledgling-enough I'd say that it has room for improvement.
It doesn't mean it bodes well or bad for the project. It just means some people left and they replaced them.
This kind of thing isn't as uncommon as you might think. It just doesn't get reported because unless the person in question is a very well known person, reporting that somebody quit their job is basically a clickbait article for news sites trying to get more ad revenue by attaching the name BioWare to an article.
I would say the logical thing to do would be to wait for information on the game itself to come out so we can judge properly for ourselves rather than predicting the doom of ME:A based on a couple of people quitting their jobs, but I've long since abandoned hope for BSN being logical =P
It's also not just the game development industry that has a high turnover rate. It's software development in general, so it would be pretty hard to lower overall turnover rate because it's not all that related to unsatisfied employees.