When [scryfall]Stone Rain[/scryfall] cost 2R it was too strong. It hasn’t been reprinted in quite a while. On the other hand, [scryfall]Demolish[/scryfall] costs 3R and despite being reprinted quite a few times, it has never really seen much play (although I do regard it as a pretty good sideboard card in certain formats). That one mana extra mana just seems to be too much. The sweet spot for this effect would probably be somewhere in between.
Suppose we double all costs. This would give us some more room for twiddling with costs. The land destruction probably wouldn’t be a good example anymore, but it would give you more room to work with various things. The way things are set right now, the room in which cards must work is quite small. Soldiers are now 1/1s, because you can’t go below that, but [scryfall]Traveling Philosopher[/scryfall] is a 2/2, because you lack the room move the numbers around.or whatever.
This would give room for things like burn as well. Now, [scryfall]Shock[/scryfall] costs one and I think that’s a fine rate. Good enough for Standard, but not gamebreaking. [scryfall]Lightning Bolt[/scryfall], on the other hand, is so strong that it warps the whole format around it. Having more options would give you the possibility to come up with more variants with these, besides just [scryfall]Lightning Strike[/scryfall], which is a fine card, but might have a little bit of room for pushing it.
How about counters? [scryfall]Counterspell[/scryfall] is UU and way too powerful, while [scryfall]Cancel[/scryfall] is 1UU and pretty much unplayable outside of sometimes bringing it in in limited.
Okay, so while I think this would be an interesting idea, it wouldn’t work out.
First, games would be much longer. Most games are now pretty good in length. The variance here is quite big, but personally, around ten to fifteen minutes (of brisk gameplay) is quite good. Longer games can be quite interesting as well, but playing too many of them is just tiresome.
Second, this would mean that there would need to be way too many lands in decks that want to actually do anything meaningful or all decks would just be full of small creatures.
Third, it would be the end of double-spelling. Casting two spells a turn is an important strategic element of the game. If everyone can only play one card a turn, many decisions are lost. Stealing initiative loses it’s meaning and the importance of drawing your spells in the right order would be further emphasized.
So, no. It wouldn’t be a good idea to move the scale that much upwards, but it might be a good idea to move it up just a notch. I do feel they often have to push certain cards too much just because they don’t have the room they need. What is the right scale? I don’t know. I’m guessing they are quite close to the right one, but the way creatures have evolved, there just isn’t room for many things, especially when designing for constructed.
For example, Dominaria has [scryfall]Llanowar Elves[/scryfall] which is a very strong card and a number of well-known players and deck-builders pointed it out as the most impactful card in Dominaria. What happened? Basically the existence of such a card means that you either have to keep the three-drops manageable, or you have to have good cards against the Elves. So, [scryfall]Goblin Chainwhirler[/scryfall] has become a dominant card in the format that pushes out quite a few others. This, on the other hand, means that many other cards become less playable as well. [scryfall]Bomat Courier[/scryfall] is going to feel the Elf-hate as well.
Ole Chains wouldn’t be required if the Elves weren’t so good, so with a different kind of scaling for mana, this problem wouldn’t exist. You’d have to be very careful with this. However, if everything cost more, the extra mana from the Elves would be less meaningful and thus there wouldn’t have to be such a strong answer for it.