Q:

Will you please insist on explanations for down-voting? 

Without explanation, a down-vote can be very like a slap round the back of the head… painful but in no way useful. 
With explanation, a down-vote can be very useful.  It would be in no way necessary to identify the down-voter, even though that would fairly obviously be preferable. 
Which would we rather have? 
Until people like Chenmunka, Dan Bron, NVZ, Helmar, or RaceYouAnytime can explain what they think makes *Why is it not…?  and Will you please change…?*  similar, let alone interchangeable, may we please not pretend this question already has an answer? 
Even ignoring their own standing or image, hands up anyone who thinks that kind of failure contributes anything useful…
Else, who thinks it helps prevent progress? 

A:

You want to know a secret? 

These are the literally the top 5 EL&U questions of all time, and every single one of them has downvotes. 
Do you care about who cast those downvotes?  Do you care why?  Do you think the authors of those questions care why? 
Would you even have known they had downvotes if I didn't show you? 
It's not about you
No, of course not.  Because they're absolutely drowned out by the flood of upvotes.  Consensus has emerged: these are good questions.  
And that's the point.  The votes aren't for you.  They're for everyone else.  They make it easy for the will of the people, collectively, to be heard.  
That was the innovation of Stack Exchange.  This is the fundamental mechanism that makes the whole thing work.  
Separating the wheat from the chaff
This system of emergent consensus is, and I'm being literal here, why you're here.   
You found Stack Exchange because you did a Google search and one or more questions came up top of the search results.  Or a co-worker told you about it, or sent you a link.  Or because you read an article in a blog or news site that linked back here. 
Well, how did that happen?   It happened because Stack Exchange makes it easy to find the good stuff, and ignore the bad stuff.  
Ultimately, when you see a highly upvoted or highly downvoted post, you don't care why.  You care the most people agree, and that takes a the impossible burden off you to evaluate every single post. 
Voting, up and down, is what makes this work.   
The bad old days
And as a corollary, anything that has the effect of inhibiting voting erodes this system.  
It makes us return to the bad old days of forums where the title of the thread might be "Got error message #e77q: too much covfefe in the yatch", the exact same error message you're getting, and page 46 of the thread may or may not contain the resolution, but you will never know, because the first 45 pages are nothing but "me too!"  and "I googled this and found nothing" and "@captmooseknuckles is a lu$3r!". 

Which would I prefer? 
So, you ask:

Which would we rather have? 

The answer is clear.   Forcing people to type a reason for downvoting will result in fewer people downvoting.  Forcing people to disclose their names when downvoting will result in fewer people downvoting. 
Fewer people downvoting is a bad thing. 
Who did you vote for? 
I contend you already know this.  And not just from Stack Exchange.  Do you ask people who they voted for in the last election?  If not, why not?   If so, what is the usual reaction you get when asking?  What do you think accounts for the fact that most ballots in major electoral systems around the world are secret? 
I'll tell you another secret.  In the last major political election in my country, the candidate I voted for did not win.  Do you care who I voted for?  Does it matter?  The other guy is in office. 
What matters is the results.  The will of the people has been expressed.  And that's the way it's supposed to work. 
Yeah, but what about my posts? 
Look at the top questions again.  They all have downvotes.  If you had written those posts, would you care about the downvotes?  Would you even notice? 
No.  It's a handful of malcontents; every crowd has a few, and the normal course of action is to ignore them¹. Same with downvotes.  You're going to get one or two, it's both natural and inevitable and completely unnoteworthy. 
It's only when you get more than a few that you should take notice.  It means several people agree something is wrong with your post.  And it's not up to them to tell you what or why. 
You were the one who posted it, right?  The onus probandi is on you.  Step back, disengage your ego, and look at the post again with a critical eye. 

¹ I walk through Times Square every morning on my way to the office, and there are literally naked cowboys, creepy Elmos, unintelligible prosthelytizers and topless women.   I don't pay attention to any of them.  You'd go crazy if you tried.  The good news is, I suppose, being in Times Square, no one would notice you'd gone crazy.