I haven't written a skin or container at all in years. I find it overly time consuming to code my own skins since the DNN Store has many to offer that fulfill most needs. However, the skins I bought from 2 different major developers have problems with DNN 8. One still uses ACTION and ACTIONBUTTON functionalities in their skins. When I contacted them about the tests on our development server, they were unaware of the problem. Since contacting them, they are now rewriting their skins to remove the ACTION and ACTIONBUTTONS calls. The second developer's menu doesn't display and they are investigating.
I really feel for anyone creating web sites that upgrades without having a development testing server like I do. If they research carefully prior to applying the latest release, they might find the problem listed or not realize what the impact is before their production site is totally hosed up.
Since DNN owns the store, has there been any proactive notification to sellers about the removal of functionalities? I know, there are plenty of release notes, etc. But as both the developer of the architecture and the wholesaler of products, I feel the wholesaler arm should be responsible for some notifications. After all, not all skin developers are worried about the changes. They might be a small shop or even a 1 or 2 time seller and then they are gone.
Lastly, taking out a features that is as wide-ranging of an impact as ACTION and ACTIONBUTTONS seems very short-sighted. You have hundreds of thousands of web sites running DNN with some skins that are very old. Sure, everyone should upgrade to mobile-ready skins that were developed very recently, but the truth of the matter is that many customers don't want to spend the money for a redesign. But they will care when the developer upgrades to the latest version of DNN and their site breaks.
I applaud the efforts to move forward, but some sort of customer feedback prior to actually making breaking changes should be put directly to your clients. Maybe taking a page from Microsoft's new playbook and have a feedback about features would be helpful. And I'm not talking about putting bug reports in. Too formal, too time intensive. Just something to tell us what's planned and open it up for comments. If you haven't used the feedback in Windows 8 or 10, you should check it out.