Because with Bush v Gore, it was a national impact where we can't allow different states to manipulate the Presidential vote. Or, in other words, states undermining each other's votes.
As we saw with the Torricelli - Forrester Senate race, SCOTUS refused to intervene when Forrester challenged the replacement of Torricelli with Lautenberg on the grounds that it was a single state issue. The same was likely true when Dino Rossi refused to challenge the recount shenanigans coming from Christine Gregoire.
By the time of the Coleman - Franken fiasco, I had hoped that SCOTUS came to realize what their inaction in New Jersey had wrought.
-PJ
What year was that? I certainly don't recall Forrester asking for SCOTUS intervention, but vaguely recall the matter of Lautenberg replacing Toricelli at a late date being approved by the 'rat controlled NJ Supreme Court.
BTW, when SCOTUS denies certiorari from a another court, they have a policy of not commenting on why they denied it. So my gut feeling is that you may not have that history quite accurately.
I can't see the legal logic in distinguishing Bush v. Gore - reviewable by SCOTUS from a state supreme court - from the Forrester-Lautenberg matter, simply because one is a state contest for presidential electors and the other is a state contest for a US Senate seat.