That said, if a patent is pending and no one knows when it'll be granted, is that not enough? Would competitors really introduce their own patent-violating version, knowing they may have to suddenly cut production if the patent goes through? Do they do that today?
At any rate, those delays seem absurd; presumably they're due to having a backlog, due to the USPTO not employing enough people, due presumably to them not having enough of a budget. Not that I'm in favor of giving money to patent-granters, though. I wonder if a fee paid by the patent-holders—say, a small percentage of the revenue from selling patented products—would be a reasonable way to fund it.
I don't know how common it is today to introduce a product while planning to cancel it if a competitor's pending patent gets granted.
The funding of the PTO has been a contentious political issue for decades.
You need a delivery mechanism that can be used quickly and reasonably safely, ideally by someone in the early stages of anaphylaxis. Taking out a vial and a syringe, and carefully extracting the epinephrine from the vial with the syringe, are not things you'd want to be doing under those circumstances. Hence the invention of better approaches.
But epipens were originally "brought to market in 1983". How are there still active patents for it? "Kaplan continued to improve his designs over the years, filing for example US Patent 6,767,336 in 2003." I wonder if the new patents cover the 1983 devices. If so, that seems like an obvious abuse of the system: keep filing a new patent for different aspects of or variations on the device, and you can multiply the duration of your monopoly grant.