A 270 offers a certain level of performance in a required long action rifle and for point of reference say with a 24" barrel. A 270 wsm doesn't require a long action making the gun shorter and faster cycling, from a terminal performance perspective the wsm will match the performance of the 270 but with a 22" barrel or it will exceed the performance of the 270 with a 24" (but because of a shorter action it is still a lighter faster rifle).
So, if you happen to live in a hunting area where short fast handling and fast cycling rifles may be considered an advantage, the wsm are just that, equal performance with about 3" less overall length and a slightly faster cycle. And every bit as competent and arguably better in long range performance considering most feel short fat cartridges burn more uniformly compared to long tall columns. One could also argue that shorter actions are stiffer.
If the 270wsm came out 80 years ago and the 270Win just 10 years ago, well the 270Win wouldn't even be brought to the market, what would be the point. It would offer nothing over the wsm. It would truly be a gimmick. Nothing wrong with using functional old technology but if I'm buying new at the exact same price I'm going to go for the better value. The 270 Win has become the gimmick, no functional advantage over the wsm.
The .270 is the real deal. The short mags are the gimmicks. If you need faster cycling just get a .270 pump. If you need help reaching out on long shots, just spend some more time at the range with your .270.
I dont think they are a gimmick. I have a 7mm and love it great shooter in a light weight fast handleing rifle. plus it puts game down hard. The 7mm is not as hot as the 270 or 300 but i think they will be around for a long time to come.
I also think the market is being hit with a lot of gimmicks recently. The only true measure of performance of a bullet is the weight of it, and the velocity at which it leaves the muzzle. The shape of the cartridge it was fired from means nothing once it is out of the barrel.
The most recent series of "gimmicks" seems to be the Ruger Compact Magnums.
There were alot of short action cartridges before Remington and Winchester started using the new propellants and brought out the WSM and RSUM..I am sure as long as each manufacturer is still in business there will be brass available but as demand falls off they will stop chambering new guns in some of these short actions.For instance the 375 RUM and 375 H&H.. The H&H has been around forever and will always be produced but the Remington 375 RUM maybe only a few people will buy it and Remington will downsize the production and eventually stop making it.