I didn't own a 30-06 until I got one as inheritance.

As for why it's not more popular anymore? I think it's due to several factors. How many millions of American men across two different generations carried an 06 to war, and then returned to use that same cartridge to hunt? That'll certainly create a large attachment to the cartridge. That, and with widely available loads with many different bullet weights, it can do just about everything. However, I think the trend for the past 50 years or so has become more specialized cartridges for certain tasks. The numerous magnums for longer range shooting, then short action cartridges for more mild recoil and/or greater accuracy, and now we have rounds designed for benchrest or accurate longer range shooting, among other smaller trends.

I'd imagine for a lot of people, there's a lot of *new* and *exciting* cartridges nowadays. To many people, I think the 30-06 comes off as well trodden ground.