Screen shot by CNET

Twitter users should be able to download their entire archive of tweets by year's end, the company's CEO, Dick Costolo said today.

During a keynote conversation at the Online News Association conference in San Francisco, Costolo told interviewer Emily Bell of the Columbia University Graduate School of Journalism that Twitter expects to provide its users by the end of the year with one of the most-desired capabilities of all -- being able to download their entire tweet history.

"The caveat is that this is the CEO saying this," Costolo joked, "not the engineer who's building this....[But it's] a priority we absolutely want to have out by the end of the year."

That news will certainly make a lot of Twitter users happy. But Costolo's comments on the growing discontent among developers and why Twitter is making the changes that rankle them may ultimately be far more important.

Over the past few weeks, many developers have complained that Twitter's moves have curtailed what they can do with their apps. That discontent was inflamed Thursday by claims by IFTTT, a service that lets users create "recipes" such as automatically retweeting any tweet by a specific Twitter user, or sending a thank you direct message to any new Twitter follower, that it would no longer be able to provide its core service. IFTTT CEO Linden Tibbets wrote in a letter to users that because of the changes, it will disable users' ability to "push tweets to places like email, Evernote and Facebook" starting Sept. 27.

But Costolo took issue with that assessment, arguing before the ONA audience that IFTTT's complaint had no merit. "I don't mean to be flip here at all," Costolo said, "but it's become a little bit [like] 'I didn't get my homework done because Twitter changed their API. The IFTTT... removing (Twitter Triggers) has absolutely nothing to do with any changes to our API, irrespective of how any change was rolled out. Zero."

This week has been something of a public showcase for Costolo. On Tuesday, he appeared on the Today Show to roll out Twitter's new "mobile-first" strategy. And later that night, he went on "Charlie Rose" and gave a 40-plus minute interview. And if one thing has been a theme across all three of the CEO's public appearances this week, it's that Twitter is dead-set on influencing the kind of third-party applications developers create. And while many who have built third-party Twitter clients may be upset at new restrictions that limit what they can do, Costolo insisted that the company's recent moves are all about expanding the value of the service for its 140 million users.

"We have tens of thousands of developers around the world who leverage [our] API and build successful businesses with it," Costolo said today. "We are going to build a platform that enables third-party developers to add value to Twitter and build into Twitter and get all [kinds of] additional value from our distribution engine."

Expanding on that thought, the Twitter CEO outlined an example of what he called the "accretive" nature of what the company is trying to foster. He explained that the NBA commissioner had recently suggested that in the future, he'd like to allow Twitter users to select the MVP award winner for the basketball league's All-Star Game. "It would be great if that was a single tweet, and the poll was right there," Costolo explained, "and that canvas changed to 'There are 90 seconds left to vote, here's the leader,' and that canvas followed [the tweet] wherever it went," such as ESPN, or NBA.com.

Costolo went on to suggest that Twitter could potentially support real-time updates and information. "Think about it....There are all sorts of amazing functionalities that third parties can build into Twitter," he said, bringing new benefits to developers and users alike. "That's the general framework for where we're going."

Costolo's explanation certainly makes a lot of sense. But the CEO has carefully avoided talking about another pressing reason Twitter has been cracking down on developers' access to the company's APIs, especially developers of Twitter clients -- it wants as much control as possible over the way people use Twitter in order to get the lion's share of advertising revenue the service generates.

In answer to an audience question, however, Costolo did allow that Twitter may well have done a "crap job" of explaining its reasoning to the developer community -- and he seemed intent on rectifying that. But he also assured the audience -- and those watching from afar -- that 2012 would bring no "more things we're going [to do to] constrain and restrict" developers' access.