If you get a chance to read the staff comments in the official notification thread, you’ll see that it was a planned change and they are not likely to change it back. The older smart apps that use it depend on a command being marked as “physical” but the problem is that only works with some switches and even then won’t work if the command gets passed through a repeater. So it’s always been very inconsistent.
There are now several Z wave plus switches on the market, including the newest GE switches, which handle double tap in a completely different way, by having the switch itself recognize the double tap and then using the newer “central scene command” to notify the hub of the double tap. This should work every time regardless of the person’s network configuration.
I realize that doesn’t help people who already have the older generation switches installed, but it may help explain why SmartThings felt it was OK to deprecate this feature at this time in the stock handlers.
I definitely agree it would’ve been better to announce the change ahead of time and give people an option to look into workarounds rather than just rolling it out with the next firmware update.