Because Hornady hasn't recreated it, it's not new hot and sexy, long case, lots of tape, low angle shoulder, just not the new trend of efficiency.
Take out the taper, put a 30° shoulder on it(would boost capacity by probably 4-5gr), neck to 6.5mm to run slippery 140gr bullets 3k fps or higher.
Wait that's a 65prc/saum? See......everything has been done, these new cartridges are just fresh revisions. The good ol 270 Jack O'Connor special will do everything a N American hunter needs out to 400y with a nosler accubond. I'd venture to say Nosler is the only ones really trying to keep the 277 afloat. They have several bullets that are heavy for cal. 170/150 ballistic tip, 165/150 ablr, 160/150gr partition.