Would the updates come faster if they charged $3 or something? You could argue that they didn't expect a million people to buy the game in beta, so releasing updates along the way can reach so many new customers. Everyone already bought it. They already got their money.
I can see gamers getting bent out of shape at the idea of having to pay for additional pieces of the game since it was unfinished and sold as unfinished with the promise customers would get the complete game when it's done. If they were going to make a few dollars for every DLC, and it motivated them to churn them out (of decent quality, of course), it might lead to them expediting the updates.
I can imagine the uproar. But I think it was already worth $20 in the condition they sold it, and if paying a few dollars for each DLC meant that they got it done rather than resting on their laurels, I wouldn't boycott them or anything.
The question is: When they release H&H, how many 'new' customers will they get, vs. just existing audience (that already paid) and the associated QC, bug fixing, etc. that goes along with it?