I hate the new popup "you can accept an answer in 10 minutes". Can you please remove it and let me accept an answer immediately?
I can unaccept it later if a better one appears.
It is our strong belief that if you accept an answer in less than 15 minutes after asking the question, you have not given the community an adequate chance to fully answer your question before rushing to accept.
You can barely test most answers in 10 minutes. Why not wait it out? It's not that hard. If you accept an answer, the interest in that question will most likely drop sharply, so you might lose answers that could have been better.
There's a reason why the 10 minute rule is there. Just be patient and accept the answer after the time expires if it really solved your problem.
Your +15 score for better answer is not really appealing enough for someone to write a good answer that will beat an already accepted one.
What matters is upvotes from other people. And the people enter the question with an accepted answer less frequently than without one.
This partly is due to the motivation why people up/down-vote. It is one of the means of expressing their opinion what answers deserve/don't deserve to be accepted. But if you already marked an answer, then there's no reason to express an opinion: you've already decided what's correct.
So by early acceptance you just get worse answers and your question gets abandoned quickly. Or turns into a flamewar, if you accepted garbage, having no time to check if it's correct.
I can't even begin to estimate the number of questions that I could have answered (at least potentially) better than the answers already there, but didn't bother because the OP had already accepted one of them. This happens almost every day when I get up, since I'm in the UTC-8 timezone and am only starting my day when the peak of SO activity is already waning.
Almost all the questions in the tags I monitor are asked while I'm asleep, so I salute any and all encouragement to slow down on accepting answers.
I suppose it all comes down to who the site is trying to primarily serve -- those asking the questions, or those coming along later with similar questions*. If the former, then people should be able to accept answers ASAP. Otherwise, the site is best served by encouraging more answers and more details in them.
* (I'm not even going to assume it's people like me, people who answer far more questions than they ask).
Just because you think the answer is right doesn't mean it is. Here is an example from an hour ago where the accepted answer was wrong on both counts. If the OP had given more time for other answers to appear, it might not have been the accepted answer. Unfortunately the OP might already be off writing code that makes assumptions based on the wrong answer, and may not come back today, tomorrow, or ever to realize they've been led astray.