Without prior knowledge of Aptana or its Eclipse-based IDE I can't provide credible commentary on the wide-ranging effects of the decision. However, several elements within their stated reason for moving in this direction are reflective of some of the key challenges involved with building a profitable business based on the open source model [emphasis my own].
The new license gives us more visibility into who is redistributing the IDE. We strive to keep a very high level of quality and polish, therefore we want to be aware of any rebranding and redistribution of the IDE.
It isn't difficult to grasp why visibility into the workings of open source software ecosystems are often obfuscated by free and open access to the source code. When licenses don't have to be purchased in order to redistribute and/or re-brand it fits that finding out who is doing so, becomes difficult. Since information of this grade is crucial from a business perspective there is motivation to own it. Precisely a notion I have endeavored to express in the past.
In this case the situation is complicated by the fact that the APL isn't OSI compliant (yet?) and it curtails distribution rights, a notable variance bound to raise red flags. However, based on the following statement from Paul Colton taken directly from his post in a forum, I'm of the perspective that Aptana has less hidden agenda than might be assumed:
We're just asking anyone who wants to distribute the IDE to contact us first. In most cases, anyone who is currently distributing will still be able to. We are also preparing a simple license that anyone can print out and send back to us that will allow them to redistribute the IDE given they aren't trying to sell it or change it in a way that we can't agree on.
We'll place this license and more information directly on our web site soon. We expect that most people that want to redistribute the IDE will have everything they want with this license. For the ones that need more attention, we'll be happy to work with them one on one.
Still, I am very much convinced that the most effective manner of maintaining that high level of polish and derivative quality assurance is by encouraging contact instead of enforcing it. It dawns on me that communities prefer more freedom of use in exchange for active participation in quality assurance. The fact that participation is a form of social capital within open source communities should be leveraged within the governance and policy of those same structures. After all, the notion of open source thrives on giving back not as charity but as an investment in collectively owned success that composes open-structure.
Hopefully, the Aptana community will find its way through this bump in the road and continue to grow as a result of it. Personally, I think it's time to embrace a new set of strategies for coping with the realities of building open source software companies, ones which prove a great deal more innovative. Strategies which are neither pacifist nor reactionary but grounded by a solid understanding of what makes open source software ecosystems tick.