We have one answer to be marked as Accepted now. In many cases there are two or more answers can be acceptable.
Suppose a problem that can be solved either by the code-solution "A" or by the code-solution "B" or by the plugin-solution "C" etc.
In that case it'd not be justified for an asker to accept only a single answer and give 15 reputation plus to his/her (the solution provider) profile. In that particular scenario there should have the privilege to accept more than one answer. For me only an upvote isn't justified enough to the solution-providers.
But to refrain from miss-use we can make it available after certain reputation, i.e. 100 or 200 etc.