To make sure we are all the same page, I am going to start with what is, logically, the definition of the MVP winner in sports:
If you could magically take each player off his (or her) team and make their team play their season all over again, which player's departure would cause that team to drop the most in the standings (i.e., incur the most additional losses).
It is not automatically the best player in the league, nor is it the best player on one of the two top team teams in the league.
Hence, it is an abstract concept and admittedly, just a guess (except, of course, your vote and mine). So, if you are using a different criteria—stop it, or you are as bad as some of the sportswriters and sportscasters and the idiots on the Internet and sports radio talk shows who get it wrong.
In the NBA, the MVP Award was voted on by the players from 1956 until 1980, and since 1981 was voted on a panel of sportswriters and sportscasters. No good reason was given for the change, but I suspect it was to bring more publicity to the award.
I think the players know more than anyone who the best players in the league are, so this change was not necessarily a good thing in terms of getting the voting correct. I also feel the more knowledgeable votes—the better. This is because everyone has their own personal likes, biases, and prejudices which inevitably affect their opinion on who is the best at something, sports or otherwise.
The only way to counter this fact is to have a large number of people vote, so that the voters' personal likes, biases, and prejudices offset each other. (For a full discussion of all of this, see my articles "Who Deserves the MVP Award in a Particular Sport" and "Who Should Vote for Sports Awards and All-Stars.)
Perhaps, the best and fairest way to determine the MVP Award (for any sport) is a combination of three different sources (after all, knowledgeable sports fans deserve a vote). A third of the weight of the vote should given to the 344 (or whatever the number it is for that league) players in the league, a sixth given to the head coaches and assistant coaches, a sixth given to 500-1000 league selected sportswriters and sportscasters, and a sixth weight given to the fans.
This way, everyone gets a vote, however, the the players, sportswriters, and sportscasters votes will count more the fans (some of whom will not be as knowledgeable as they should be). (This is similar to the NFL All-star selection, which, in my opinion, is a good voting system.)
No matter who does the voting (players, sportswriters, sportscasters, or fans), anyone who votes and is not objective can turn the voting into a popularity contest. And since everyone is capable of doing this (i.e, not being objective), I do not see this as a factor for not the letting the serious fans vote.
Maybe, just maybe, with this system, we will finally get the MVP Awards correct in the sports every year. But, I doubt it since the chances of the person that I vote for winning every time is pretty slim.