Note that a commission will make that decision in Colorado,, not a state legislature. The reason: the old way that resulted in political gerrymandering, with the majority party drawing congressional borders so there are "safe" districts for their partisan Congressional candidates. It is gerrymandering, the practice that over the years both parties have carved out so many safe districts that any sort of bipartisan agreement on anything in Congress has been nearly impossible. In a gerrymandered district lopsided to favor a political party, the primary becomes the reals election, and the most radically partisan gets to be the candidate in the general election. and in a lopsided district, the minority party is often just baying at the moon,. The independent commission that draws the boundaries for a congressional district is more likely to make elections make competitive throughout the process and extremists would be less likely to win. Candidates would have to broaden their appeal. The winners in this process are the independents and more bi-partisanship and the losers are hard-core party loyalists and extremists of both wings of the left and the right.