Blade & Soul it's not really the cost that makes upgrading a problem, it's how it all works. First there's important materials we need, in some defined end-game content, which leveling players can't do. Clearly the idea is that leveling players are to buy those items from the end-game players, so said end-game players feel rewarded for doing that content.
Problem is those end-game players need those items too, and lots of them, especially with the insane content release schedule you're going with, resulting in the in-game supply not really being sufficient for the demand. Those items then get priced based on the earning potential of end-game players, not the leveling player, Buy Blade and Soul Gold and the end-game players see it as their money making cash cow, so want the prices to stay high, and complain if anything happens to reduce their value. For leveling players such items are out of reach of all but the hardcore grinders, and wallet warriors since you don't shy from putting such items into the cash shop, and heavily cash shop influenced events, like the trove event. Plus aside from paying for those materials, we're suppose to pay the upgrade fee as well. When we can farm the items we need, and just have the upgrade fee to worry about, the money we get as a leveling character would be enough, it's when you also expect us to buy things from others that things get messed up.
After that, there's the upgrades themselves, which at times, are actually downgrades as immediately after going through a breakthrough/evolution stage, our equipment has lower stats than it had before. It wouldn't be until we are at about the next breakthrough/evolution stage that there's much of a bonus, and even then, it may not seem like much. Honestly, a bit of streamlining by removing some of those stages would be a good idea.
Then there's the required weapon, which we need the right one of for our class (nine currently, with more likely to come), and often can't be traded, even within our account. With other games you can have multiple ways of getting a single piece of equipment, Blade and Soul Gold or roughly equivalent equipment. Get it as a drop, craft it, farm tokens to trade with a NPC, or buy it from another player, as usually it only binds to a character after it's equipped. Due to how things work in other games, even failing to get what you wanted can be a net positive, and be used to get what you wanted in the end. Here, there's often really only one way, and when we don't get the weapon we need it's pretty much useless to us, making it a complete loss, and highly discouraging. If they could at *least* be traded within our account (along with other things, like sealed soul shields, equipment XP gems, etc...), it'd really help with playing alts, but nope, no can do. Selling the ones we didn't want to others could even help fund upgrades, but we of course can't do that either, as they're character bound. Soul shields can be even worse, I've had about ten, or more of every other piece before getting even one of the one I wanted, and with them having random stats, it may still not give me what I wanted. We can't trade those either, and can't do much with unwanted ones, but grind them for powder that I tend to have plenty of.