Why have people reacted to this vote as if it was the (future) vote on the Article 50 legislation? It isn't.
There are any number of reasons why MPs might vote against a Labour motion demanding that the government publishes its Brexit plan, amended by the government to endorse the government headline timetable of triggering Article 50 by the end of March 2017.
Some may not want the Brexit plan published (although unlikely as only Clarke from the Tories voted against) but others (Ben Bradshaw is one and I think Plaid and the SNP) wanted a government white paper on the Brexit plan and thought the Labour motion was not demanding enough. Others think it is a mistake to trigger Article 50 in March because they think nothing will happen until after the German elections and the government will have started the clock too soon and wasted limited negotiating time.
It says very little about the eventual legislative vote. It certainly doesn't mean there are 89 MPs who don't accept the referendum outcome.