Are recent changes in SO customer- or system-driven?
I suspect a mixture of both, but it's very important to understand that the "customer" in this case are the thousands of people who come here daily for help, not the experts who work here.
From the perspective of an outsider who merely wants an answer to their problem, and google promises the information is here, having few to no off-topic comments is a plus. It means less irrelevant material to read and comprehend.
From the perspective of the system - the maintenance and care thereof - it makes sense to encourage users to have such discussions where they won't need to be moderated.
I think that the system has to balance the needs of several aspects of the site:
- Technical requirements
They are just looking for help. However, the largest portion of site traffic comes from them, and they are the target of the advertising. This is, in theory, the primary monetary motivator of the site.
- Easily readable
- Clean UI
- Attractive not just in looks, but functionality
- Draw experts in who may just be visiting for the first time
Without experts, the content wouldn't be created, and visitors wouldn't get answers to the questions which aren't already answered (or are hard to find if answered).
- Easy to ask and answer questions
- Easy to help "judge" the correctness and quality of other's contributions
- Easy to help with common moderation tasks as a group
- A game system that fulfills aspects of Self Actualization (prestige, curiosity, experience, connection, etc)
There are some activities which shouldn't be delegated to the wisdom of the crowds, and which may be irreversible. These activities are performed by diamond moderators and some employees. They get to be the bad guy for egregious acts of abuse or misuse, as well as other aspects of moderation that need to be dealt with daily. Further, they are the first line of support for users who believe there's a problem with a post that can't be readily handled by the community.
- Easy to moderate
- Tools that detect trends and problems prior to regular users noticing
- Direct line to each other and the main team for additional direction and discussion
The programming team, company, community evangelists, server/internet infrastructure, etc need to be taken into account as well. Some things can't be solved technically, or would require more time and effort than the problem warrants. Some problems can only be solved - or even approached - through human exchanges.
- Company benefits
- Clear direction
- Resources to maintain focus and forward movement
- Community feedback
- Ability to help direct the growth of the company
Recent changes are both customer and system driven, however, the weighting probably tends more towards visitors than experts, and this is probably why the current friction exists.
However, it must be understood that these two changes you specifically call out merely change how the experts interact with the system. The @ issue is cosmetic - it doesn't get in the way of interacting with the site. The chat issue is a suggestion - a gentle push in the direction they would like you to take - but not a shove. Neither change removes functionality.
Yet both changes should directly impact how visitors engage with the site.
So there are some tradeoffs, but on balance the pain caused is expected to be less than the benefit gained, when you take into account all the customers the system is expected to cater to.