Healing matters in a team context, in most cases it doesn't matter much in a 1v1/small skirmish context.
Look at the game I listed. None of them are the price of a full-fledged, AAA, single-player (or dual single/multi) experience. Similar games before Overwatch's release also received huge backlash for charging a premium price for a multiplayer-only game, granted I couldn't list them by name because honestly FPS games aren't really my jam anyway so it hasn't stayed in my mind. In a vacuum, I don't necessarily disagree with you, games like OW or League or whatever are ridiculously good value if you get into them and enjoy mashing games out, but it is overpriced compared to the rest of the market. Most MP-only games charge a relatively low price ($20 max) for the complete package and/or make their money off microtransactions that don't affect the core gameplay (cosmetics and grind shorteners for in-game loot/currency). OW charged $60 on console on release, and you had to pay attention to pay down to $40 for PC, and it's still going for $30 a year later. Full-price games like that ala CoD and Halo tend to have extensive 1P/coop campaigns in addition to multiplayer (and Halo campaign coop is fucking awesome so dun hate).
... Except for the part where consumers are apparently perfectly happy with paying the premium for Overwatch in particular, in large part because Blizzard is a popular developer known for consistently putting out excellent games and to publicly bash them would probably be career suicide for gaming journalists, which completely justifies Blizzard's decision as a business to charge a premium price. It doesn't hurt that Overwatch is also a pretty good game.