Personally I get why 5v5 was done, but I utterly hate it. It removes all the things that made Overwatch 1 so cool compared to other FPS to me:
Slow TTK as a result of two tanks in front of the team.
High focus on healing, as someone who enjoys playing healers in all games this was heaven to me.
Lower focus on personal damage contribution and aim, as syncing ults, creating trap spots and selectively bursting targets was how you got kills, not just aiming.
In total, this resulted in me and my friends easily having a game we could all enjoy on a few characters each (me on Moira, Mercy, Torbjörn, Symmetra and Bastion, for example) and talk shit while just playing the entire evening.
This whole “social” spirit was lost as they slowly pitched the balance towards faster and faster TTK, and ultimately with 5v5. It’s a “competitive FPS” now, but honestly, I don’t need a competitive FPS. Never did. I did however need a social fun low-stakes FPS, back when OW1 came out. And that spot is no longer filled, sadly.