Totally agree with all the above, great question OP and great responses. I personally research other games, not only because of the wealth of ideas to think about but even more importantly, sometimes they are fun to play themselves!
I'll add a little personal story.
Back in 1996-1997 for my senior software engineer project at undergrad school I wrote a game prototype. In fact, that was the most recent game I've worked on besides my current game, I took a 15 year break but am back in this with a passion!
My project at the time was a 2D tile-based graphical MUD / multi-player game. It took me a year but I successfully completed the prototype. It wasn't a complete game, but it was playable in terms of movement, a few basic monsters and attacks, and some early sandbox features. A talented high-school art student worked with me and did a great job with the 2D graphics. It supported 50 players per instance or so and was UDP based. A top-selling game publisher was impressed enough to consider hiring me as a junior game programmer but for various reasons that didn't work out.
I graduated college and was planning to continue working on my game another year in my part-time and releasing it. But, then I learned about a new game called Ultimate Online was coming out soon. That discouraged me enough to immediately stop, as I didn't think I could compete with a professional game studio working on something similar to what I wanted to create.
Looking back, my game concept was actually much closer to Minecraft than UO, and there is some non-zero chance had I just kept at it another year or two it would of turned into something like Minecraft but 10 years earlier. Now of course that is all very speculative; good games take a lot of work and my point isn't to say I would of been successful. Rather my point is to say sometimes your games are not as close to others as you think and they are original and innovative in their own way even while sharing a lot of overlap.