There have been some Democrats who were strong supporters of shall-issue, but even so, they voted for a rabidly anti-gun Senate leadership. The GOP leadership was openly pro-gun. Not all of them truly see the light on the issue, understanding how fundamentally important it is to ensure that we maintain an armed citizenry, but some do. And the rest understand the political reality.
The shall-issue bill passed in Minnesota because over the last seven years, through three election cycles, the pro-carry advocates turned out people at the caucuses, the primaries, and the general elections, and put pro-carry candidates in office.