Rods always used to be 10ft. Then with people starting to fish longer range, the length went up. Most of the modern shorter rods are good for 100yds or so - so enough for most waters. Easier to get in cars, allegedly easier to move when packing up to move swims (tho how when the rods are folded being 12” shorter makes much difference ??). Arguably easier to put pressure on fish due to leverage. On trend with current fashions!
12ft rods cast further, help if you have backside snags and need to lean out, don’t need specialised luggage, more choice. Better line pick up.