Diablo 3 is going to take another step towards making the endgame easier. In 1.05 Blizzard is going to reduce monster damage by ~25% and nerf the hell out of a bunch of the most problematic defensive skills. Long term this has to be considered a good move because when you consider that PVP is supposed to be a big focus of D3 sometime in the near future you must consider balance from a class vs. class perspective and not just a player vs. monster perspective. You simply can't have always-on abilities that reduce damage by 43% (like Prismatic Armour for the Wizard with decent gear) and imagine that somehow this will work out fine when other classes have no similar abilities.
I suspect that Blizzard needed to solve two problems at once. First off, when you can select an ability that reduces damage by 43% the idea that you would choose anything else is ludicrous. This means that the wide variety of spec options touted by Blizzard at the outset is not particularly applicable because either players are totally invincible or these sorts of abilities are mandatory - there is no middle ground. There are plenty of other abilities that are on the chopping block too and thankfully Blizzard seems to have consistently targetted the ones that were most over the top. Even Demon Hunters and Witch Doctors, who had by far the worst damage reducing abilities, had their best ones reduced in effectiveness somewhat. These changes will definitely open up PVE specs a lot and make it much more reasonable to run more utility or damage dealing powers in place of the current strategy of two attack moves and four defensive powers that people seem to favour. Adding another attack spell to my bar increases my offensive power a little by increasing my flexibility but the change is small - defensive powers need to work the same way for specs to have a lot of variety at the top end.
The other problem was pvp of course and in particular the Witch Doctor and Demon Hunter were an issue. Pets work fine for tanking monsters but if you build a pet class and assume that you can give them weak personal mitigation abilities because their pets can tank you are setting them up for failure in PVP. Players ignore pets and will always focus fire the summoner so Blizzard absolutely needed to bring overall mitigation levels down so that Witch Doctors weren't hilariously flimsy when faced with an intelligent opponent. Demon Hunter designs face an entirely different problem because Demon Hunters are either invincible or made of paper and have little middle ground (Barring 4p set + perma Gloom which is clearly absurd and needs to get bugfixed). DH do not have enough passive defenses and any attack that would threaten a tough class with death would outright kill a DH. While PVP is supposed to be fast paced I don't think that Blizzard really intended to make a class that was a one hit wonder by design.
The changes they have outlined seem very good from both a PVP and PVE perspective. The endgame will certainly be easier overall as even the classes facing the most serious nerfs will be slightly better off and the other classes will be improved but not so much so that it is a problem. Because Blizzard is also adding a few new ways to dial up the difficulty I think PVE will remain challenging and fun. Whether or not Blizzard can actually get PVP balanced well remains to be seen but I am certain they can manage to make something fun and addictive out of it. PVP was never particularly balanced in D2 and it was still a blast as long as you weren't fighting against people with duped gear so I am sure D3 can be just as good and likely much better.
One last note though: Due to pet Force Armour mechanics these changes will actually make pets die more easily rather than the other way around. In order to maintain relative pet toughness the 10,000 baseline for pet Force Armour needs to be reduced by the same % that enemy damage is reduced. Reducing enemy damage by 25% means nothing if you are reducing an 80,000 hit to 60,000 and then only allowing 10,000 through regardless.