To make Colorado a more desirable state for candidates/campaigns, thereby increasing our influence on the national process. For example, on March 15 of this year there were primaries in Florida (D246 delegates/R99 delegates), Illinois (D183/R69), Ohio (D160/R66) and North Carolina (D120/R72). If Colorado (D78/R37) awarded its smaller pool of delegates proportionally, we’d be less likely to draw attention from campaigns and thereby influence the national discussion.
Parties will tell you this binds delegates whose candidates may have dropped out. What they won’t tell you is there are rules on unbinding delegates in those circumstances.