Feel free to try, not that you need my permissions or anything, but I'm pretty sure your proposal addresses the wrong problem.

I don't think that the "not professional" reason gets used as an excuse to clamp down on high quality, but home/development questions. In fact, my experience has been the opposite - the regulars will save high quality questions from that requirement, rather than using the "professional requirement" to slam shut good, quality questions. I have personally edited out "at home" from questions to save a good questions from closing, and I've witnessed other high-rep users do the same thing with similar good, but out-of-scope questions they felt added value to the site, in spite of not being strictly professional. And this is above and beyond what happens more regularly with reopen votes and the close vote review queue.

Given that, I think it would be really helpful if you find some examples of questions that add value, but got slammed shut simply because they're not professional. I really doubt you'll be able to find many. What I see far more often is a bad question, or question about "doing it badly" getting slammed shut for not being professional, the OP saying they are, in fact, a professional, and then being pointed towards the meaning of "professional" meta thread, with butthurt usually ensuing. Of course, butthurt usually ensues anyway, because it's evidently not nice to tell someone why their pile of shit masquerading as a question is a pile of shit, even when done politely and constructively, but that's a bit of a tangent.

I really do think that questions are judged on their merits as it stands now, and the professional close-reason is used as a supplementary close reason most of the time. There isn't really a clear "your question sucks" close reason, but the professional capacity close reason is fairly close, especially if you read the meta thread on what "professional capacity" means in these parts.

The data you cite would be interpreted more accurately if looked at through the lens of drive-by window-lickers becoming more active as the high-quality regulars (and even just anyone with half a clue) becomes less active. It is my opinion that the window-licking horde of crap-flingers are driving off the people who would otherwise be asking quality questions, but I will grant that it's not something I can prove, or offer more than anecdotal evidence for.

In any event, I think that's where the effort needs to be focused. Slow the influx of crap, and hopefully retain more of the regulars we have, or allow new people to grow into that role. (Ways to do that, like stopping unregistered users from asking questions have been suggested and not implemented by SE.) But I don't see us retaining existing members worth a damn, or growing new ones while the front page is full of embarrassing fail. And not just embarrassing fail from a professional IT perspective, but from any perspective. Seriously, right now, all the Server Fault main page does is validate my low opinion of humankind. And having said that, that is why I can't recommend Server Fault to friends and colleagues or co-workers any more. Not because I'm worried that someone will hurt their feelings or close their question, but because I think they'll look at the main page of the site, see the river of shit and lower their opinion of me and my skills accordingly.

Feel free to try, not that you need my permissions or anything, but I'm pretty sure your proposal addresses the wrong problem.

I don't think that the "not professional" reason gets used as an excuse to clamp down on high quality, but home/development questions. In fact, my experience has been the opposite - the regulars will save high quality questions from that requirement, rather than using the "professional requirement" to slam shut good, quality questions. I have personally edited out "at home" from questions to save a good questions from closing, and I've witnessed other high-rep users do the same thing with similar good, but out-of-scope questions they felt added value to the site, in spite of not being strictly professional. And this is above and beyond what happens more regularly with reopen votes and the close vote review queue.

Given that, I think it would be really helpful if you find some examples of questions that add value, but got slammed shut simply because they're not professional. I really doubt you'll be able to find many. What I see far more often is a bad question, or question about "doing it badly" getting slammed shut for not being professional, the OP saying they are, in fact, a professional, and then being pointed towards the meaning of "professional" meta thread, with butthurt usually ensuing. Of course, butthurt usually ensues anyway, because it's evidently not nice to tell someone why their pile of shit masquerading as a question is a pile of shit, even when done politely and constructively, but that's a bit of a tangent.

I really do think that questions are judged on their merits as it stands now, and the professional close-reason is used as a supplementary close reason most of the time. There isn't really a clear "your question sucks" close reason, but the professional capacity close reason is fairly close, especially if you read the meta thread on what "professional capacity" means in these parts.

The data you cite would be interpreted more accurately if looked at through the lens of drive-by window-lickers becoming more active as the high-quality regulars (and even just anyone with half a clue) becomes less active. It is my opinion that the window-licking horde of crap-flingers are driving off the people who would otherwise be asking quality questions, but I will grant that it's not something I can prove, or offer more than anecdotal evidence for.

In any event, I think that's where the effort needs to be focused. Slow the influx of crap, and hopefully retain more of the regulars we have, or allow new people to grow into that role. (Ways to do that, like stopping unregistered users from asking questions have been suggested and not implemented by SE.) But I don't see us retaining existing members worth a damn, or growing new ones while the front page is full of embarrassing fail. And not just embarrassing fail from a professional IT perspective, but from any perspective. Seriously, right now, all the Server Fault main page does is validate my low opinion of humankind. And having said that, that is why I can't recommend Server Fault to friends and colleagues or co-workers any more. Not because I'm worried that someone will hurt their feelings or close their question, but because I think they'll look at the main page of the site, see the river of shit and lower their opinion of me and my skills accordingly.