I understand where they were coming from when they made both the weaksauce MC rules, and the hit-or-miss Hybrid rules. They were afraid to break the game.
With multiclassing, they were worried that if it was too easy, everyone would do it in order to poach a really juicy power, and it would become a "must have" option for the hard core optimizers, which, in turn would trickle down to the casual optimizers and power gamers. So instead, they made it really unattractive. And Paragon Multiclassing sucks.
Like AbdulAlhazred pointed out, back in the PH1-only days, there were probably a few corner cases where it would make sense. Not anymore; feats have become too valuable to blow on junk options like powerswaps that replace options you already had with something usually less good.
If those feats got you something else, then maybe. If they got you skill bonuses from your multiclass trained skill list, bought you additional encounter, daily, or utility powers like the Skill Powers do for Utilities, or even let you take both and choose which to use from a given slot, then, maybe.
Oh, and if Paragon multiclassing didn't gimp your character out of 3 abilities, and make you trade in an at-will... yeah, maybe. As has been pointed out, if you're multiclassing, a cross-class PP will almost always do better things for you than dipping back into your multiclass for powers will.
Hybrids and their issues are a different matter entirely. Clearly, they were afraid of creating loopholes to making monstrously broken characters. Ones that could effectively cover an entire role all the time and gain a little extra from another would be a problem. Allowing a character to add Hybrid Talent twice is not a good solution to this though. There are loads of builds that suddenly become better than being single-classed. It's less of a problem if you make them wait until Paragon to do it, but it's still not an ideal situation concerning balance.
Some of the Hybrid options will let you do viable things with your character, fair enough. Some will make you useless, and they warn you about that in the section on doing that, again, fair enough. Some of the combinations though, seem like they've been gimped just for the sake of gimping them. Some of them would be more viable if they didn't suffer so badly from MAD-ness.
I don't know what I do want to see, exactly, but I know that I don't want to see multiclassing become what it was in previous editions (i.e. "sweet 1-level dips" into Barbarian, or half a dozen PrClasses in 3e, or near-painless Thief multiclassing in 2e).
I think ideally, a modular approach would be neat. What class features are swappable between classes, sans-gimpage, and what is the balance-cost to do so? Can I make a Ranger that swaps Prime Shot for Hunter Weapon Talent? Can a bard give up Majestic Word for a striker mechanic like Soul of Sorcery?
In the meantime though, I want to know how e-classes interact with what we already have with respect to multiclassing and hybridizing. Unless this new multiclassing system mentioned at DDXP is going to be so good that it can replace the two systems already in place, then I would be hesitant to introduce a third way of doing it.
Ultimately, I like what Mr. Mearls has done, and I think whatever comes will be interesting and well-put together, but there is always that nagging little voice in the back of my head casting doubt. Until I see it, that is...