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.
That's a pretty good summary I think. There is definitely some benefit to "modern" case designs (and the SAAMI specs/tolerances that come with them).
The .270 was/is a great way to get a medium weight bullet moving quickly. It doesn't do heavy for caliber high BC bullets well (in factory configuration) and those bullets aren't readily available in factory ammo. Rebarreling, handloading, and ideally a longer magazine are required to get a .270 to do what a 6.5 PRC does out of the box with factory ammo.
Before we all had rangefinders and scopes that dialed correctly, we guessed that the deer was at 300 and if it was at 350, that might be 7" or more error with a .308win. It's more like 4-5" with a .270, a real tangible difference.
With rangefinders and good scopes, the flat shooting nature of the .270 is much less of an advantage than it used to be. Other cartridges now are just as effective out to moderate ranges with less recoil/powder burned, and/or longer barrel life. At long range, the .270 is at a disadvantage to cartridges like the 6.5 PRC and similar that are spending that recoil and powder (and COAL) budget on getting a heavy high BC bullet going at medium speeds. If you need three more clicks on your turret at 400 yards, that is a tiny price to pay for better wind performance, higher retained velocity, and a heavier for caliber bullet impacting the animal.
I think there's something to be said also for starting a heavy bullet a little slower and what that allows. A bullet that starts at 3200 FPS probably needs to be on the harder/tougher side if you plan on shooting something at 50 yards. That means as that velocity decays (and it will decay quickly with a light for caliber low BC bullet) those wound channels from a hard bullet going slow at longer range will get small.
A wound channel from a heavy, soft bullet that starts below "extreme fragmentation" velocity and stays above "underwhelming upset" velocity kills very consistently from very close to very far. The far end is helped by the bullet having a lower "low limit" velocity, and also by high BC helping retain that velocity further out.
That's all possible with a .270, but it takes quite a bit of work to get there.
