Kumo's advantage is actually pretty logical when you consider they've got the most access to ore and they're located next to the sea which means what trade they do perform is cost-effective.
They'd have easy access to all the same trading partners Konoha would, save for Sunagakure and those landlocked nations. In fact, because of their coastal location their trade should be somewhat superior to Konoha's because sea routes are cheaper than land routes.
Furthermore, Kumo is described as mountainous but not desolate like Iwa.
They're described as having many rivers, and that's rather important. It means cheaper transport throughout the country and sources of water for crops.
There are likely a couple valleys running through the country such as the Valley of Cloud and Lightning, and if they happen to be river valleys they'll be very suitable for produce crops. The main point is still the rivers though. Rivers are a boon to civilization, in fact many ancient civilizations were supported by their respective rivers; Mesopotamia -Tigris & Euphrates, Egypt - Nile, China - Yellow River, etc.
I would agree that Konoha is more readily settled, but Kumo doesn't have the worst location by far.
With the frequency of wars those mountains are also a fairly good deterrent against invasions, which is why most battles would've been fought on the low-lying areas e.g. Ame and Kusa.
War is probably the most important factor as to why Konoha isn't comparable to Kuma. Konoha is a central power, they're between all the nations and as a result have fought with all the nations over the past 3 Ninja wars.
We know that they fought Kumo in the 1st ninja war
We also know that they fought Suna, Ame and Iwa in the Second Ninja war.
We also know they fought Iwa, and had some skirmished with Suna, Kumo and Kiri in the third War.
Not quite sure who Kumo was fighting during these wars, but because of their location its unlikely that they would've had as many enemies to fight as Konoha, meaning the burden of war on them would've been less.
War also plays a critical part because War need weapons, and Kumo is the country with the most capacity to produce them. Their economy would get boons from the sale of weapons and ore during times of peace, and as for times of war...well all trade would've halted so they wouldn't have ended up any worst than the other nations.
America for one good huge boons to their economy from selling weapons to the allies during the world wars before they'd joined the wars themself.