Well maybe n ot in a ton of AAA games but still even heartstone is made with unity, and a lot of more indie type games but there must be a reason they use ot over unreal.
I tend to see 3 big reasons:
- C# is a bit easier to get into / more forgiving than C++
- Unity has much larger pre-developed asset library (big plus if you do not have your own art department)
- Unity does not require royalties if you are a paid game - Unreal does. But -- Unity locks key development items behind their paywall instead (debuggers, optimizers, etc), and if your game is free, there are no royalties due to Unreal -- so not a huge difference, but a distinction none the less.
I'm not a game developer, but from what I've gathered -- if you are doing a AAA quality release, or want top notch graphics will all the bells and whistles that come with that -- Unreal is your only choice. That said, to have the team to implement all those bells and whistles, most small indie shops just won't have the chops to dig into all of that in a game of any substantial size or complexity -- hence why you tend to see larger developers using it and not a lot of small indie guys.
But if you want to crank out something quick, or are a smaller shop and have limited resources - C# lends itself well to that, the larger asset library of Unity helps you plug holes, and especially if you are just doing a 2D or retro/pixel art style game that doesn't require anything too graphically demanding... Unity is the way to go.
I wouldn't call Unity second fiddle to Unreal - they are just different engines that are suited to different tasks.
