Yeah, based on Tigris' explanation (which matches what I've seen from other friends who play MMOs), the comparison of encounter/daily powers to MMOs cooldowns seems pretty off-base.
As Pedr wrote, with 4E encounters and dailies you pick your spots to optimize value.
Sometimes that DOES mean using them early, particularly because strikers want to be cutting down the number of enemies ASAP. Reducing the number of enemy actions and attacks is always a good thing. And that is the most similar to MMO cooldown powers.
But most other powers which provide situational benefits or can be multiplied in effect based on positioning (getting enemies or friends bunched in the AoE, for example) are more powerful when you set them up. And synergistic play in 4E often meant characters coordinating- for example one character pushing or sliding one or more enemies to set up an ally to get extra value from a key daily. Or the Bard I played in one campaign using a power to let the whole party move off-turn to get into perfect formation for the next character to pay that off with another power.
Mearls' summary there seems like memory changing in hindsight. Not just because his release timeframe seems simply mistaken.
I'm not sure what he thinks MMO-style play means. The closest elements I recall from that were...
a) hoping to capture recurring subscription money (which they did, with all the groups I played with- EVERYONE used the character builder),
and
b) hoping to have a VTT which would allow people to play remotely with their old friends and family around the country or the world (which would also be more likely to get buy-in on said monthly subscription, as it would be a service more akin to playing EverQuest online with your friends, rather than just books in your house).
If by "MMO-style" he means "online play that you pay for on a recurring transaction basis" that makes sense. If he means in terms of play style, I don't think that comparison holds up. Playing 4E is not much like playing an MMO in terms of what your actual activities are while playing. How you spend your time and how you interact with the world, game, and other players. The kinds of decisions you make.