Syncretic Evolution and Hive Minds
I like that the second top comment on the hive mind one is calling them out for missiles being worthless.
Those quotes suggest that only small areas of jungle or glacial ice are removed, and somewhat reinforce my theory. The last one is too generic to draw any conclusion from. Demolition can mean anything from carving out a small road to exploding an entire hillside and beyond.
Y'see, that's what bugs me. We're already able to build full-scale mining centers in mountain ranges.
For me, this reinforces what forsaken was saying but even moreso. Remember that Iron Age civs are already said to have spread across most of their planet, so tiles don't make a ton of sense as proportionate geographic regions. More likely they represent something a bit more convoluted, or their exploitation represents a really high bar for output.
So with that in mind, having your output on a planet blocked by a giant rock physically occupying too much space doesn't make a ton of sense to me. I'd think it'd have to be a much more advanced issue, which means dealing with it would probably have to be similarly complex and nuanced. The kind of thing that doesn't really occur to you until you're an interstellar empire.
I'd be all for a mod that adds a few more blockers, some of which might have very high tech limitations, and made all planets size 25. Earth could have some mountains and oceans that need clearing.
Why? So the planets are even more alike than they already are?
Beyond Earth had this problem, and it really sucked a lot of flavor out of the game. It was there to an extent in previous Civ games, but the last few had enough luxury resources to keep you settling near specific tiles in order to keep your people productive. BE did away with luxuries and had only a half dozen strategics, most of which you didn't really need unless you were at war and weren't really essential even then. The net result was that the majority of your cities weren't really there for a particular reason or purpose beyond "generate stuff," which in turn usually sucked the personality right out of them.
So with that in mind, I'll have to second extreme wariness at making planets more similar. I'd love to have more to do with them, but I dunno if it'd be worth it if doing so turns each one into even more of a shapeless blob in your empire.