You left out the Rasmussen poll, where Clinton LOSES to Trump. That's relevant to the GE. It's only one poll but it points to Clinton's vulnerability.
And you left out the information that her average margin against Trump is only +6.5, while Sanders' is +13.4. THAT is relevant to NOW and the choice that Californians, Oregonians, West Virginians and others are about to make, and it is relevant to the GE as well. Who is best positioned to beat Trump? Who doesn't just beat but demolishes Trump in national polls? Who draws independent voters (40% of the electorate), young voters and new Democrats?
You are jumping to the GE before the nomination process is over, and are simply ignoring the strongest Democratic candidate against Trump. This is very relevant to the GE if your view is typical of the Democratic Party establishment, as it seems to be. The large margin of difference between Sanders and Trump (Sanders average +13.4 over Trump) is going to all but vanish in the GE, if Clinton is the nominee. All that strength that Sanders has built up for the Democratic Party will largely go away, because Clinton is so unpopular and so distrusted; she will be left with her current base, which is mostly within the Democratic Party and nowhere else, and a whole lot of iffy voters and anti-Clinton voters.
There is also a psychological element to that margin (for Sanders), as well. It's not just that they don't like Clinton, but many of these independent voters, young voters and new voters are increasingly aware of the efforts to disenfranchise them, which were so dramatic in New York and Arizona. They have no reason to come out for Clinton, on policy or on attitude.