The Senate is supposed to consent to the nominee, not the nomination process. They should vote on whether they think the nominated person should be a justice, not whether they like the current president. Announcing that Obama's nominee will be opposed whoever it is goes beyond the constitutional authority of the Senate.
Unfortunately, there's not much to be done about it right now. We do live in a representative constitutional democracy, but it's maintenance requires a certain level care and faith. Laws alone aren't enough to hold it together. If you think the Senate should rubber stamp all nominees, or you think the Senate should delay all nominees, then you don't really care for our democracy. If the Senate itself thinks that way, we're in trouble.