For starters, the game's primary competitors are both AAA games, and considerably cheaper to boot. CS:GO is $15, and TF2 was $20 before it went F2P. Both made by Valve. Overwatch's main competitors are no knockoffs: one is a pillar of the eSports community, and the other has had a long and successful life, much of it as a F2P game.
CoD and Halo both have single-player campaigns. I pay $60, but I get a lot of content. It might not be that great of quality, but it's still additional content that the developers worked on and put in the game. Sometimes it's good (CoD 4: Modern Warfare), sometimes not (CoD: Ghosts), but you still get what you pay for. Hell, even Splatoon has a single-player mode for $45, and they don't even have microtransactions like Overwatch does.
You're absolutely right; quality does come at a price, but there comes a point where you stop paying for quality and start paying for the name on the box, and that's the problem I have with Overwatch. There are good, quality alternatives to Overwatch for considerably cheaper, and that makes the pricing point and the microtransactions come across as Blizzard trying to have their cake and eat it too.
Overwatch could be good. It could even be great. But the barrier to entry is just too high when compared to its peers.