If one substitutes 3e for 4e, I have essentially the same perspective.
I offer my input out of goodwill to try to make the game and the hobby better, but WotC will have to work very hard to get any of my money. The only compromise I'm interested in is compromising between what I already have and perfection.
There's something else on which we agree on! D&D Next stands or falls on
whether it is a good game.
Not at all. In 1e and 2e, in my experience, multiclassed PCs constituted about 1 in 6 of all characters I DMed (this over many years of DMing). That makes them fairly rare compared with 3rd edition in particular.
In addition, a 2nd/3rd M-U/Fighter was generally weaker in a combat situation (albeit more versatile) than either a 5th-level mage or a 5th-level fighter.
XP for 2nd level MU: 2500
XP for 3rd level fighter: 5000
XP for 3rd level fighter: 4000
Possible XP range for 2nd/3rd MU/Fighter: 8-10,000
XP for 5th level fighter: 16,000
XP for 5th level mage: 20,000
16,000 XP = 3rd/4th MU/Fighter
20,000 XP = 4th/4th MU/Fighter
Tell me, were you using house rules to make multiclassing a weaker option? Because I have problems seeing a dart-specialist or even a second rank polearm specialist 4/4 MU/Fighter as weaker in combat than a 5th level MU. And I'm trying to see even the combat advantage a level 5 fighter holds over a 4/4 fighter/cleric. (OK, +1 to hit. W00t!) The F/MU has armour issues of course.
Then there was human dual classing. Where for the low, low sum of 2001 XP you could get your first two hit dice as d10s, and be a weapon specialist when you had nothing better to do.