I think the point made in the article is a good one, and totally valid. Whether or not the roleplaying is 'good' or 'bad', the palyer is making an attempt to add something extra. A good DM should respond to this. Whether 4e encourages roleplay or not seems like another issue.
I have only DMd until very recently. I prefer 4e for a few very simple resons, one of the most important being I can remember all the rules off the top of my head and I no longer have to stop the game to look things up in order to make a ruling. I haven't found any difference in the level of roleplay at my table. But that may have a lot to do with how I DM. When players roleplay I look for ways to respond. When they don't, I actively encourage them to do so (as the roll they are about to make may depend on that +2 I give them, or that i lower the DC from difficult to medium or that I simply don't let them try and intimidate anyone if they aren't going to tell me how they do that).
But that's neither here nor there. The advice given is good advice. I've felt this accutely as I've recently found ways to play as a player. People talk about Grind and 4e a lot, but how is a combat not going to feel 'grindy' when the DM insists that every simgle monster fights until the very death despite the fact the 'monsters' are clearly going to lose, and that is painfully apparant from about the third round. Here was the scenario: PCs on our way to next town. Bandits on the road asking for a toll to be paid. As hardy tough adventurers we roleplay before combat letting our enemies know that we don't fear them, that we aren't going to pay anything and we are going to teach them a lesson they are never going to forget. Cue the fight. DM misses everyone on all but one attack for the first 3 rounds. At the end of the third round the first Bandit dies, another is bloodied. My fighter had been constantly mocking their futile efforts at trying to hit us. The bandits fought on stoicly and in silence. They didn't say anything back, even once. To push my point home I decided to unleash a Daily which raised everyones defenses by two and heckled them again telling them that if they were feeling frustrated before, it was going to get even worse now, we even invited them to run away while they still could. Nothing, silence and they carried on fighting ... until every single one of them was dead. Not really how I would expect a road bandit to behave when he realised he got into a fight he was going to lose. So needless senseless grind. But worse, the feeling of discomfort and frustration that I spent the entire fight talking to myself. Not even a miserable ' Shut your face you goddam big mouth, I'm going to cut your guts out and stuff 'em down that big fat mouth of yours!'.
So, yes, i think it's a key aspect in any DMs style, responding to anything a player throws out there. That's the point made. And it's a good one.