How do you figure?
I've been a game designer, coding for a UO shard for a lot of years, and I can tell you the situation from the point of view of the developers:
They designed a game, tried to balance it, with a reasonable balance between risk, reward, and fun. The amount of work that you have to do before players start really testing it, is huge. By the time that you really get a good idea of how things work out, a lot of stuff has been built and used by a lot of players. So, you kind of have to guess how the game will play out, how things will balance, etc.
This being pretty far back in MMORPG history, they didn't have all that many examples to look at, so they had to guess. Guess how players will play, guess how players will select powers and slot them and use (or not use) them (remember how long it took them to fix Fear powers, and I think that they've only fixed one Phase power).
Now, a year or more into the game, they see that.... they guess well on some things, and not so well on others. The game is doing okay, but there are some clear balance issues. Basically, they did not anticipate, or want, Tanks herding 200 Wolves and jumping into Dumpsters. Leaving aside the aggro and target caps that they put in, they never wanted Tanks to be able to do that, defensively. Or Blasters to 1-shot most mobs by 6-slotting with Damage, 6-slotting Hasten, Aim, and Build-Up, and always being at the damage cap. So, the game was not playing the way that they thought was good.
Now, at this point, they absolutely have to change some things. Some options are:
1: Their own vision of how the game plays. Frankly, they did this to some degree, but I agree with them that accepting Tanks who can go AFK in the middle of 100 even-con mobs is not acceptable game balance.
2: Some major game design changes, such as the more mobs are attacking you, the more likely they are to hit you (you can dodge a couple of guys shooting at you, but you can't dodge 100 with the same level of ability), or some other way to limit defenses. And then they'd have to do something about the damage-capped Blasters. And about Controllers. And about... forget it. Too many changes, and you get back to the starting problem: you're guessing how things will work.
3: Powerset balances. This actually did happen, it was called the GDN (Global Defense Nerf). I agreed with it also, and you can see that even now with just SOs, characters can still be built to play at +6/x2 (maybe even higher), and IMO that is clearly enough defense considering how they wanted the game to play.
4: Slotting balances, otherwise known as ED. I don't really agree with the "drop off a cliff" curve that they used, but the concept is the best thing that they could have done, for one simple reason: it forced the players to slot powers more like the Devs expected the powers to be slotted when they balanced them. Given that the design and balance of the powers took months if not years, and it would take months if not years to rebalance powers so that the game plays with more balance in risk-reward-fun, and it takes a lot less time to put in ED, clearly some form of ED was the best solution.
I know that players at the time were all like "But why do we have to play the game the way YOU want us to play it!!", but that misses a major point: The reason that you have to play the game the way the Devs envision it, or at least be strongly influenced to play it, is because that's how the Devs designed the game and balanced the NPC threat, the rewards, the missions, etc. ED is a lot smaller change than re-balancing everything else around the realization that min-maxing with 5-6 Damage SOs, or Resist SOs (with Stamina 6-slotted). The game at the time was unbalanced, and even most of the players who complained about the solution at least were willing to admit the problem. What they did not see was that from the Dev side, putting in the solutions that the players wanted were more of a gamble, and a lot more work. It didn't make sense for them to do a lot of extra work with less expectation of a successful balancing adjustment, when they could put in the relatively-simple ED.
And if they had explained this clearly at the time, I think that it would have ended up pretty much a non-issue.