Yes. Encouraging users to wait 24 hours before accepting an answer is good.
The Problems For Answerers
I am not primarily concerned about the effect on answerers, though I think those exist (fastest gun syndrome, discouraging answers after the accept).
The Problems For Askers
This is about teaching users - especially new users, who are pretty much the ones that do this - that the first answer isn't necessarily the best and they should stick around.
Because remember, we're mostly talking about noobs here. If SSD accepts an answer immediately, no one's going to sweat him about it, they would figure "OK obviously this question was one that needed a slam-dunk answer and he got it let's move on." The situation we're talking about is a brand new user who is excited, knows nothing about the site, happens across us, posts a question, and the second they get an answer they accept it - and, most likely (as in provably the most common case in the site analytics data), scuttle off never to be seen again. "Deep engagement" is by far the exception not the rule, a huge percentage of our site users have 10 or less rep.
New users are unclear on the concept. They aren't sure if it's one person who answered them or the community. They don't know if that person who answered knows what they're talking about or not. They got an answer and they're off! They feel lucky, many internet sites you post a question to and don't get an answer ever or for weeks.
So what we probably want to do with these folks is say "Hey - you may want to wait a day because you'll probably get multiple good answers and you probably need to think about them."
While it's technically true "well they can always accept a different answer" - that's a statement for experienced site users. Noobs don't know that they can, they may not even return after that first frenzy of clicks. Heck, frankly a new user who figured out to accept an answer is above the median in terms of being on the ball.
The Problem For Later Readers
And then also, you have the problem of answers with a bad/fast answer accepted but much better answers below. Sure they get upvotes, and you can bounty them, and blah blah blah. But again, that's experienced user inside baseball stuff. The next excited new 5e player is going to see a search result in Google, click through, see the thing with the green check, and scamper off themselves. Having poorer answers as the accepted answer does degrade the site's content.
TL;DR
You need to keep in mind the lightly engaged nature of real Internet users and encouraging folks to slow down a sec to think about theirthe answers they're getting and engage a little more with the site is 100% net positive. I can't think of any down side except we have to spend effort writing comments saying "hey consider not accepting immediately", which is minor.