Thing is, you can circumvent not being able to place mountains. You can still just smite stuff to make holes. Those are just as efficient.
Actually, the reason why I didn't think Smite was a problem was simple: Every time I've tried it in my testing games, the strategy of "smite until something is isolated" goes horribly wrong as the game simply loves to place more tiles there at the worst possible time. Hell, I nearly lost a game once because of that, and it only took ONE turn of the wrong tiles being there to undo my plans.
There is one major thing I would change about Smite though; not the cost or anything, but instead make it only work if it DOESNT cause any of the tiles that are 1 tile away from the tile it's smiting to be cut off from paths to the rest of the map. There really shouldnt be any bits of the map floating off on their own anyway, unless something like the Midgard Serpent causes it. This, actually, I think might be an important change. Smite should be able to allow you to do different things with the map itself, funnelling units around, but.... yeah, it should NOT allow you to actually cut off even a small part of it, because that's the exact point when Smite goes all cheesy.
EDIT: The more I think about this particular thing.... not letting Smite cut ANYTHING off (AKA, testing the pathing of the 8 tiles around the smited tile to make sure that each one can reach all the TCs), the more important I think this is. And why not simply have the mountains and lakes do the same thing? The player could then use chokepoints with all 3 options if they really wanted to (and lakes/mountains could still be removed on Hard or higher), but they wouldnt be allowed to simply cut off any bits of land entirely. Chokepoints are a fine strategy and not cheesy, by my view (and they CAN go horribly wrong, as I've found out!), but yeah, outright cutting off access to tiles COMPLETELY is not at all a good thing, and is the core of the cheese tactics.
And as for the 4-mountain thing, it works like this: Drop a town center. Put 4 mountains around it. ......done. You now have a pretty much invincible "town" that can keep you in the game.
You know, an idea occurs to me.... why not simply just disallow ALL of these things.... mountains, smiting, lakes..... within a certain radius of a town? With the exception of the 3-AP building smite, of course. Could make it so that it you cannot do these 3 things if they're only 5 tiles (or less) away from any town center.
AND you could then make it so mountians/whatever cant be placed adjacent. Or something like that.
Frankly, I cant actually imagine a USE for mountians at this point, but it'd keep them there, for those that want them for whatever reason. I dont think I've ever found even one use for the things that is NOT a cheese tactic, to be honest. Wheras I use smite all the time without actually causing units to not be able to attack things (but then I'm also not actually cutting parts of the landscape off when I use that for anything, aside from games during the beta where I did that to test what would happen).
Though I'm still all for simply leaving them out. The discussions here is getting into the realm of making LOTS of changes, or changing other aspects of the game "because mountains", which strikes me as a bad idea.
And if lower-level players need the things.... the original idea of simply having them available on medium or less seemed fine to me (and I dont use the things regardless, myself). I'd rather just have that happen, instead of going through bunches of OTHER changes, which can then lead to MORE problems, which can lead to MORE changes, all because of a tile that seems to have few viable (non-cheese) uses ANYWAY. Just leave the accursed thing in on the lower difficulties and be done with it, I say.
Not to mention.... I'd be against too many changes to the basics now that the game has released anyway. Tends to not go over well with players that werent in the beta and also those who arent often on the forums here (and thus wont see WHY they happen, they'll just suddenly see features pulled/altered for no reason). The change of removing mountains/lakes from even easy/medium was likely not a good idea from that standpoint.