Lord Mhoram
Hero
This is informational, so hopefully it can be taken that way.
Things in 3e that broke that camels back...could be seen as
No real limits on multiclassing and making it very easy to do. 4e reintroduced restrictions, or more stringent restrictions on multiclassing to try to make it less easily abused.
Classes as true archtypes. In otherwords, along with making it so that characters were not a conglomeration of ten different classes and such, to make it so that the classes were stronger in and of themselves. Hence a fighter was truly someone who had trained for years and could really fight! as opposed to a multiclass character that had simply gotten to be a fighter over the past day because...well...just because.
Characters and monsters were NOT the same types. They were different and hence used different rules. Aka...1e. Monsters are not heroes, and heroes are not monsters.
I like what you pointed out here, very insightful. I had left D&D shortly after 2nd ed hit. I found Champions/Hero system, and that became my One True RPG for decades. When 3rd came out I was skeptical (as I felt 2nd didn't change the stuff I felt should have changed, and changed things I thought worked) - but I read the PH - and the specific things you mention above as the things 4E was designed to compensate for - is exactly what I loved about it. I read the multiclassing and prestige class rules and though "This is the D&D for me!". Not surprisingly I didn't care much for 4E - but that is all about taste and playstyle.
I really can't wait for the Next core books to come out - I am really interested to see what it looks like with the modules there, and what options are around.