Well, the original developers of the series went bankrupt. Tells you everything about the standing of the series among Nintendo customers. (Of course, I am certain the "Switch-effect" will do wonders for sales numbers of the new game.)
Also the vote asks us to name our favourite game of the show and even if one likes Mario & Luigi, chances are that they like Zelda or Metroid even more.
It is also likely that fans of JRPGs like Dragon Quest or fans of fighting games are not that much into the Nintendo franchises, thus Dragon Quest and Mvs.C gaining more votes since they are not cannibalizing each other as much among their respective fanbases.
The poll doesn't ask us to rank the games. So in theory it could be possible that Mario & Luigi, albeit not being the first choice for most people, could be the second choice for everybody!
Yes, this is a very extreme scenario but we don't know the answer since the poll isn't asking us anything but our single favourite game.
