My brief experience with this stems from League of legends, I had decided when I first started I would never spend any money on the game, then a skin I reallllllly like went on sale half price so I decided to dump in 10 bucks and buy the skin on sale, I then had half of enough for another skin in RP so I spent another 5 bucks and bought a full price skin, overall I spent 15 dollars where I would have spent none if that initial skin hadn't gone on sale. Then a month later they did an 80% sale on a bunch of skins so I dumped in 30 bucks and purchased like 10 of em then had enough left over for another half a skin so I waited until one I liked went on sale.
Overall I spent 45$ on a free game entirely because of the sales prices, I think it was a good call on their part, plus after I started using the system in order to take part in the limited time sales I became more comfortable with it, the first time around it was kind of stressful typing down all that personal information and shit but second time about I just clicked a button and got my stuff, once I was used to this system I ended up spending another 20 bucks on skins and characters that had been recently released at full price.
From that little bit of hindsight on my prior experiences with it I would say sales are a great way to increase your customer base as well as encourage previous buyers to continue, I've spent 65$ on a free game where as I refuse to spend 60$ on a triple A game, almost entirely because of sales. I mean I guess EAs logic would work if NO ONE ever had sales so you never had to compete with them but that's simply not the case.